Supertrapp Internal Disc Exhaust System
SUPERTRAPP INTERNAL DISC EXHAUST SYSTEM
CW EVALUATION
A good set of pipes?
AFTERMARKET EXHAUST SYSTEMS are extremely popular. and with good reason. Combining a throatier exhaust note, lighter weight. attractive looks and an affordable price with the potential for improved performance always is appealing.
Recently, Super Trapp (3910 Seaport Blvd., West Sacramento, CA 95691;916/372-5000) introduced its internal-disc silencer, a design that incorporates the company’s trademark diffuser-disc tunability with an attractive, canister-style muffler.
We ordered a complete system for our test Suzuki GSX-R750. that model being a common candidate for an aftermarket pipe. Like all SuperTrapp street systems, the entire pipe and silencer, excluding the muffler core, are crafted from stainless steel. Appearance is excellent, thanks to the stainless construction and clean welds. And on the Cycle World scales, the SuperTrapp system is nearly 10 pounds lighter than the stock set-up.
Unlike the stock exhaust, which uses collars to ensure proper fit, the SuperTrapp's head pipes simply slide into the corresponding exhaust ports. Flanges and Allen bolts secure the pipes in place. The rest of the system-collector pipe, silencer and clamps—fits correctly, and is an easy bolt-on proposition.
Although jetting information is supplied. SuperTrapp claims that its system can he tuned at the silencer by adding or subtracting diffuser discs. This is important. because rejetting a GSX-R. or any modern sportbike. can be a difficult, time-consuming headache. According to SuperTrapp. adding discs increases the sound level, raises the powerband (less bot tom-end. more top-end perfor mance) and leans out the carbure tion. Removing discs does just the opposite.
With eight discs in place, the GSXR promptly fouled its sparkplugs. After installing new plugs, we added the additional six discs provided with the system. Even with 14 discs in place, the mixture was exceedingly rich, and the motor stumbled badly off idle. We had to order an optional sixpack of discs ($14.50). Adding five of the discs cleaned up the carburetion nicely, but highlighted another problem: noise. With 19 discs in place, the exhaust note is just too loud for street use. So, yes. the system is tunable by adding discs. But. using the minimal number of discs, then rejetting the carbs, is the way to go if you want an acceptable sound level. And, as noted, this is far from a simple procedure. At least the bike's smooth, wide powerband wasn’t hindered by the SuperTrapp: The GSXR remained as easy to ride as stock. with no noticeable loss in torque.
But even in this 19-disc configuration. the SuperTrapp's performance gain over stock was negligible, certainly not enough to justify the added decibels. We tested the stock exhaust back-to-back with the SuperTrapp system at the Carlsbad Raceway dragstrip. Stock, the GSX-R posted an 11.10-second run at 1 23 mph. Fitted with the SuperTrapp pipe, it ran 1 1.02/126.
Something else to consider is the discoloration of the system. Heat turns the stainless steel of the headers and collector pipe an attractive, golden-hued brown. Unfortunately, only the final 4 inches of the silencer—the area encompassing the diffuser discs—changes shade, while the rest of the silencer retains its original color.
On the plus side is the SuperTrapp's cost. Replacing the stock GSX-R exhaust will cost $403 for the silencer, and $78 1 for the entire system. Available at $160 for the silencer. or $430 for the complete system. the SuperTrapp is significantly less expensive than the OEM item.
That price advantage, together with its good looks and its weight savings, works in favor of the SuperTrapp. Now, if it could just be madequieter without having to resort to rejetting, we’d be first in line. E3
