Sweet dreams are made of these: a (relatively) easy-to-develop, insanely popular product that is amazingly profitable. Naturally, we're talking about aftermarket pipes for cruisers. Following in the footsteps of Harley accessory sleepwalkers, many companies are seeing massive opportunities to sell replacement exhausts that, presumably, add character in the form of increased exhaust noise and, if they're lucky, horsepower, by freeing up the movement of expelled gas. One waking fantasy so far not realized is the instant delivery of big power. The aftermarketers are learning that Japanese exhaust systems are extremely well engineered, hampered only by regulations, not know-how.
Scan the advertising and you'll notice that exhaust systems come in many flavors, including both full and slip-on styles. Slip-on mufflers are just that: silencers (or sometimes just plain tubes) that replace the stock items but retain the factory head pipes; slip-ons are usually cheaper to buy and easier to install. The Kawasaki Mean Streak we used for this test precludes a simple muffler swap, so a full system it'll have to be. We found seven manufacturers willing to bear scrutiny and one that declined. (Cobra's Ken Boyko said the company categorically refuses to participate in pipe "shootouts," but he did offer to send a Cobra Fi2000 fuel-injection remapper as a consolation prize.) These seven pipes are broken into two basic categories: 2-into-1 megaphone systems and 2-into-2 drag pipes. A 2-into-1 system starts with individual head pipes that join before the muffler. Generally, this kind of system benefits from strategic tuning -- by carefully choosing the head-pipe diameter and length (and striving to keep those pipes the same length, as only the Muzzys system does here) as well as the collector's distance from the ports, it's possible to tune the system so naturally occurring exhaust pulses help extract burned gas from the combustion chamber. (The steel breadbox beneath the swingarm on a stock Mean Streak attempts to do the same thing, as well as reduce noise.)
No escaping the noise police....
No escaping the noise police. Our Intercomp sound-pressure meter sampled the pipes' aural effluvia.
Drag pipes are generally open tubes with a constant diameter from head to tip. All but two of the systems came with internal baffles -- corrugated inserts that help reduce noise and add some necessary back-pressure to the system. We're mystified by the popularity of straight, unmuffled drag pipes. Typically, they don't perform well over the entire powerband -- in fact, they're not supposed to. Drag pipes were developed to help produce peak horsepower in a very narrow rpm band -- perfect for dragracing -- and have become popular in spite of their performance shortcomings.
About our test: We mounted each system on a Kawasaki Vulcan 1500 Mean Streak according to the instructions and noted how each fit the bike. Then the pipes were tested on our SuperFlow CycleDyn eddy-current dynamometer using a controlled run -- a hybrid of inertial and loaded theologies that produces accurate, repeatable data. The pipes' effluvia was sniffed by our Powertrain Electronics lambda reader -- a sophisticated oxygen sensor that tells us the overall fuel/air ratio during the dyno run. In addition, we performed noise tests at the dyno using our Intercomp digital sound-pressure meter. Our protocol was one used by racing organizations -- the microphone was 20 inches from the pipe outlet and 45 degrees off-axis laterally. Three very precise measurements were taken: at idle, no load at 4000 rpm, and by using the dyno's load cell, maximum load at 4000 rpm. (Basically we set the dyno to hold 4000 rpm in fourth gear and pinned the throttle. Whee!)
Our tests sampled each pipe's...
Our tests sampled each pipe's acoustic signature: one at idle, one at a steady 4000 rpm with no engine load and one at the same speed at max engine load. (Click on any chart in this article to see a larger view.)
Finally, we road-tested the pipes on an eight-mile course that included suburban streets and a brief highway run. Why so short a loop? We wanted our tester to try every pipe in a single day so that comparative, subjective impressions would be as accurate as possible. Also, we needed time to fuss with the Cobra Fi2000 to set baseline fueling curves for each pipe. Thanks to the lambda readings at the dyno, we could quickly home in on the high-speed enrichment necessary with each pipe, but the road testing allowed us to twiddle the Fi2000's low-speed adjustment for the best throttle response.
Our pipe sampler offered humanity in the microcosm -- you've got your good, your bad, your average, your indifferent -- and having emerged on the far side of psychoanalysis, we're happy to have discovered each systems' true colors, the genuine personality beneath the flash of chrome and beyond the window-rattling bluster.
Style: 2-into-2, unequal-length drag pipes with standard baffles. Optional tuning cores (restrictors) can replace the baffles. Full-coverage integral heat shields.
Price: $425
Weight; difference from stock (pounds): 7.9; -23.8
Installation notes: Pretty simple, actually, with everything lining up well. The flange heads, upon which the standard Kawasaki split-exhaust flanges bear, are slightly too deep, so there are too few threads engaged on the studs. It's nothing major, but a couple of millimeters less depth would help. At the other end, the pipes are held together with a simple bracket, with another bracket from the top pipe to the OEM hanger. Nylon locking-nuts are used on the brackets, a no-no. In a high-heat environment, the nylon will melt and the nuts will lose their sense of self-locking.
On the Dyno: Thanks in part to the integral baffles, the Chambermaids offer a good, reasonably smooth set of dyno curves. The torque trace hits an early peak at 2250 rpm and drops to follow the stock output, showing an improvement of seven foot-pounds at 3750 rpm. The Bubs tail off considerably at the top of the range, making them one of the few to produce less-than-stock power at the rev limit. As with all the pipes tested here, the Bubs produce maximum power on the stock fuel-injection settings (but work best on the road with some enrichment) and display a commendably flat fuecurve. (Some of the drag pipes cause the mixture to swing radically from too rich to too lean through the run.)
On the Road: Loud, just on the border of obnoxious. Slightly more raucous at idle with motorboat overtones, the Bubs fall into a nice cadence above 2000 rpm at partial throttle. As with most drag pipes, they get a bit raspy at full throttle and high rpm. Low-speed throttle response is good and the bike feels plenty quick throughout the powerband. There is very slight popping on trailing throttle and no effect on cornering clearance. Fi2000 Recommendations: Low speed, 5:00; high speed 1:00 (minimum).
Final Grade: B
Good as drag pipes go, the Bubs have a decent power curve and enough noise to make you persona non grata with your sensitive neighbors, but not so much you'll get kicked off the block. Good build quality at an average price for the group.
Style:. 2-into-2, unequal-length drag pipes with standard baffles. Full-coverage integral heat shields.
Price: $415
Weight; difference from stock (pounds): 15.4; -16.3
Installation notes: Straightforward. The single steel bracket for the front and rear pipes fits well. The tubes have massively welded heat-shield brackets. A big single bracket mounts individual pipes to a footpeg carrier. It's slightly cramped behind the bracket (between the pipe and the swingarm), but not radically so compared to the others. Captured mounting-nuts are welded to a thin steel strip and seem to need a third hand back there. There are steel lock-washers instead of the dreaded nylock nuts. (Yay!)
On the Dyno: A near copy of the Bubs' trace, the Hard-Kromes have an early peak, followed by a slight dip toward stock-level torque and a second rise in midrange. The only difference is the Bubs pull out a lead at the top of the rev range, while the Hard-Kromes are very close to stock. Judging by the fuel/air trace, the Hard-Krome pipes hit a funky resonance between 4500 and 5000 rpm -- the mixture goes significantly lean -- that we could not tune out with the Fi2000. Adding fuel at the top made the peak overly rich and didn't significantly improve torque in that range.
On the Road: Although the decibel meter shows that the Hard-Kromes are the quietest of the drag pipes at idle, they've got a chirpy, harsh sound. Once up in the rev range at partial throttle, their sound changes to a more mellow cadence that's not at all unpleasant. At full throttle, however, these pipes turn unruly, loud and blatty. With the help of significant low-speed enrichment, this setup is fairly responsive, though we'd put it just a hair behind the Bub and well back of the 2-into-1 systems. No change in cornering clearance.
F12000 Recommendations: Low speed, 6:00; high speed 3:30.
Final Grade: B
A good, all-around drag pipe with decent manners and a fine build quality. Quirky mixture requirements suggest fine-tuning the injection might be a challenge.
Style: 2-into-2, unequal-length drag pipes with standard baffles. Full-coverage clamp-on heat shields.
Price: $440
Weight; difference from stock (pounds): 12.8; -18.9
Installation notes: Clean and simple. Jardine employs a simplified mounting scheme, with the lower pipe mounting to the upper pipe via a welded-on flange, while the upper pipe mounts to the stock exhaust carrier with another welded-on tab. Everything fits well, with no stress or strain on the parts. SAE hardware is used, but at least the bolt securing the two pipes together is fitted with a standard steel lock-washer rather than nylock nuts.
On the Dyno: The Jardine pipes are conspicuously smaller than their drag-pipe competition and the baffles are more restrictive, so the rather dramatic fall-off in top-end power is not unexpected. This lack of high-rpm flow affects fueling, too. With these pipes, the Mean Streak goes rich at the top of the rev band, well past a best-power mixture. Unless you fit a DynoJet Power Commander -- which can reduce as well as add fuel flow, while the Fi2000 can only add fuel -- the Jardine system will be hard-pressed to compete on peak power. At the bottom of the range, it's better news, with a torque curve that hovers just above the stocker's without unfortunate artifacts.
On the Road: Very mellow for drag pipes, with slight popping on trailing throttle. The Jardines have a surprisingly good low-rpm response but fall off tremendously above 4000 rpm. Think of them as kinder and gentler drag pipes -- to be filed under oxymoron along with "truly attractive politician." A modest increase in low-speed fuel enrichment cleaned up off-idle responsiveness. Cornering clearance is unaffected. Fi2000 Recommendations: Low speed, 3:30; high speed 1:00 (minimum).
Final Grade: B-
A victim of compromise, the Jardines are quieter than the other baffled drag pipes -- even if the sound meter says they're louder than the Hard-Kromes at idle -- but they sacrifice a lot of top-end power for a modest reduction in racket.
Style: 2-into-1, equal-length collector system with a baffled megaphone. Full-coverage clamp-on heat shields.
Price: $400
Weight; difference from stock (pounds): 6.4; -25.3
Installation notes: No problems on the installation as the pipe fit the bike beautifully. The individual head pipes are slip-fit into the collector, which is integral with the megaphone-style muffler; we saw no evidence of exhaust leakage. The muffler bolts to the stock pipe-hanger using OEM hardware. A plate is provided to move the unsightly regulator/rectifier from its mount on the left side of the bike. One shortcoming: The design of the rear pipe routes it directly over the oil-filler cap, making access with the pipe in place difficult.
On the Dyno: A beautiful curve, with more midrange surge than stock and an even, well-distributed reserve of torque. Muzzys' pipe posted the best peak power in the group, but because it lacks drag-pipe artifacts at low rpm, it missed out on the max-torque number. A lot of the pipe's efficiency can be seen in the fuel/air trace, where it maintains an even keel throughout the rev range; a lot of pipes in this test saw huge swings that were difficult to tune out with fuel-management software.
On the Road: This is a sweet-sounding, superior-performing pipe for the Mean Streak. It has a healthy holler at high rpm -- and is maybe a bit sharper on trailing throttle than we'd like -- but you can sneak through the neighborhood at partial throttle if necessary without scaring cats or setting off car alarms. On the highway, the Muzzys' tone rumbles along sweetly just beneath the wind noise. Throttle response and power delivery are superb, with the midrange improvement seen on the dyno clearly present on the road; the Mean Streak feels stronger and punchier all through the rev range. Cornering clearance is unaffected.
Fi2000 Recommendations: Low speed, 4:00; high speed 1:30.
Final Grade: A
This is without a doubt the nicest pipe in the test. For performance and sound, Muzzys' product rates a full A, no question, although we're tempted to dock it half a grade for the oil-filler clearance deal. The performance is there in spades and the price is right, so for now we'll look the other way.
Style: 2-into-1, unequal-length collector system with baffled muffler. Full-coverage clamp-on heat shields (some parts provided after our evaluation commenced.)
Price: $500
Weight; difference from stock (pounds): 9.9; -21.8 (as delivered)
Installation notes: Fairly simple. Our sample's head-pipe heat shields arrived too late, and the secondary shield -- intended to cover the lower portion of the front pipe and the collector -- fit poorly. Connections among the four pieces -- the two head pipes, separate collector and muffler -- were tight fits, with the only clamp at the muffler. The system includes a bracket for moving the regulator/rectifier from stock position and was the only one to come with replacement exhaust-port gaskets. There were no nylocks in sight, but the slot in the muffler designed to accept the mounting bolts was too narrow and had to be opened by a B.A. screwdriver.
On the Dyno: The Roadhouse 2-into-1 posts a dyno trace nearly as good as the Muzzys', which is really saying something. The torque curve follows the stocker closely through 3000 rpm and then charges off the blocks, opening a 10 foot-pound gap right at 3500 rpm. From there up, the trace edges down toward the stocker but never falls below it, posting a 3.6-horsepower increase at peak. Sounds small, but it's that midrange surge that makes the Mean Streak take on a new personality.
On the Road: Call it mellow, slightly boomy. Where Muzzys' pipe has a slightly hard-edged sound, the Roadhouse burbles and thrums throughout the rev range. This pipe apparently stays close enough to stock in terms of mass flow that you could almost get away without remapping the injection. But with a slight amount of low-end enrichment the Roadhouse performs better, with a crisper response and no popping on deceleration. The lower heat-shield touches down just before the footpeg feeler, so watch out. F12000 Recommendations: Low speed, 4:30; high speed 1:00 (minimum).
Final Grade: B+
A good all-around performer with a relaxed note, the Roadhouse just misses an A grade because of its slightly below-average fit and finish, however, some finishing touches on this just-run system are expected.
Style: 2-into-2, unequal-length drag pipes, no baffles. Full-coverage clamp-on heat shields.
Price: $380
Weight (pounds); difference from stock: 10.6; -21.1
Installation notes: The twin pipes mount to a massive bracket, which weighs nearly three pounds by itself! Because the rear pipe's heat shield is slightly too long, it's necessary to mount the muffler so far back that its hardware-store carriage bolt is barely engaged in the mount. The clamps holding the mufflers to the head pipes do not close tightly enough to seal the junction properly, and they're secured with self-immolating nylock nuts.
On the Dyno: Carnage. The Slashers obliterate the Mean Streak's low-rpm torque. Once beyond an early peak, the torque curve dips below stock until approximately 3500 rpm and then springs to life, outpacing the unmodified bike's reading by 3-5 foot-pounds right to the redline. At peak, the Shoguns make 3.7 hp more than the OEM system. You can see the mayhem created by the open drag pipe in the fuel/air trace; it's off-scale lean (more than 16:1) at the top and bottom, while going fairly rich (12:1) right at 3500 rpm.
On the Road: Pretty much what you'd expect from an open-end drag pipe -- very loud any time the engine is running, with a particularly chirpy note at idle and trailing throttle. Poor low-speed throttle response is never completely cured by changing the fueling -- adding a lot of low-speed fuel only made the transition to midrange and top-end even more ragged. An unpleasant experience for all but the most din-addicted riders. No change in cornering clearance.
FI2000 Recommendations: Low speed, 6:30; high speed 5:00.
Final Grade: D
Knocked down for build quality and noise, the Slashers are only partially redeemed by good high-rpm power. This is a classic drag pipe, with all the strengths (OK, one) and weaknesses (many more than one) in evidence. Recommended only if you hate your neighbors.
Style: 2-into-2, unequal-length drag pipes, no baffling. Full-coverage integral heat shields.
Price: $465
Weight; difference from stock (pounds): 12.1; -19.6
Installation notes: A poorer fit than expected for the price. The individual pipes (which have integral flanges where most systems reuse the standard Kawasaki split flanges) bolt to a massive steel plate that hangs from the stock pipe mount. Unfortunately, the mating bracket on the inside face of the lower (front) pipe is welded several degrees out of alignment, which could create stress cracks over time. Nylon locking-nuts are used.
On the Dyno: Offering near-stock performance at the bottom of the rev range, the Mean Mothers only get cooking above 3750 rpm, and maintain a slight edge over stock to the 6000-rpm rev limiter. They make 4 hp more than stock at peak, but fail to match the unmodified bike's torque peak. Watch what happens to the fuel/air ratio and you'll understand the SuperTrapp's performance -- it swings from off-scale lean until 2250, then shoots up to 10.2:1 at 3250 rpm (well rich of best power) and back to full-lean at 5000 rpm. No amount of injection skew could get the top-end rich enough without drowning the midrange; clearly this pipe needs a DynoJet Power Commander, which has more tuning flexibility, but we suspect it'll take quite a bit of work to get the Mean Streak happy with this pipe.
On the Road: Raucous, nasty, blatty -- all the things we dislike about unbaffled drag pipes -- plus it's unusually farty on trailing throttle. It sets off car alarms even at idle and very light throttle. There's a tinny sound at idle that turns into a clacky tone at partial throttle and eventually wanders into typical drag-pipe rasp at max throttle. The low-end and midrange responses are definitely down from stock -- though with the cacophony the bike can feel faster, rest assured it's an aural illusion. We had to crank up the low-speed fuel compensation to make this bike/pipe combination even remotely happy. Cornering clearance is unaffected.
F12000 Recommendations: Low speed, 7:30; high speed 5:00.
Final Grade: D-.
Uproariously loud with quality issues, combined with so-so dyno performance, the Mean Mothers are perilously close to a failing grade.
Marc Cook is a regular contributor to Motorcycle Cruiser and our sister magazine Motorcyclist as well as other automotive and aviation publications.
For additional evaluations of, comparisons of, and shopping advice for motorcycle gear and accessories, see the Accessories and Gear section of MotorcycleCruiser.com.