Suzuki's latest-generation GSX-R1000 is unquestionably the top-nut liter bike on the market right now. It turns like a crazy straw, stops faster than Ashlee Simpson's prerecorded vocal track and, with a horsepower rating just north of 161 at the wheel when it rolls out the dealer's door, it hits harder than a baseball bat. This stellar power output is no doubt aided by the factory exhaust system, which was designed and engineered for Suzuki by the legendary Japanese tuning firm, Yoshimura. As well as it works out of the box, though, the big Gixxer's factory exhaust is nonetheless still subject to government-mandated noise and emissions controls that limit ultimate performance, not to mention the, um, "space-age" styling that has an effect not unlike a sharp stick in the eye. Clearly, many GSX-R owners are going to be hitting the aftermarket for a replacement exhaust.
If you're one of these riders, read on. To help you choose the ultimate exhaust system for your Gixxer, we got together with horsepower heavyweight Lee Shierts of Lee's Performance Center (www.leesperformance.com) in Charlotte, North Carolina, and exhaustively tested seven of the top systems on the market to see which was best. Using Shierts's own personal 2005 GSX-R1000 as the rented test mule, we designed a battery of tests to insure the most complete and objective results possible. First, Shierts started by unpacking and inspecting each system, weighing and measuring each to gather comparison data and also taking detailed notes on fit and finish as each pipe was installed on the bike. All eight systems (the factory exhaust plus seven aftermarket options) were run on the same day by Shierts on his in-house Dynojet dyno, using 93-octane pump gas and individualized injection maps for each pipe to ensure a consistent air-fuel ratio for comparable results. We also measured the sound pressure level (decibel rating) for each pipe. This level was checked with the bike at constant throttle at 6000 rpm, with the sound meter located two feet away from the exhaust canister outlet.
Finally, in addition to the strict dyno data, we wanted to make sure we had some measure of real-world performance testing in the mix, as well. For this, Shierts ran each pipe at the drag strip at Rockingham Dragway ("The Rock") in Rockingham, North Carolina. Thanks to the support of track owner Steve Earwood, and with much assistance from ace mechanic John Russell, Shierts was able to make a total of 41 passes using all seven systems over the course of two days.
For the drag racing portion of this test the bike was set up according to AMA/Prostar SuperSport racing rules, which allow the use of VP Racing MR9 race gas and a minimum ground clearance of three inches. That means our test bike was lowered a few inches from stock to help Shierts launch harder, so don't feel bad if your personal GSX-R doesn't click off times like these. (Not to mention that Shierts is a multi-time national motorcycle drag racing champion.)
Shierts started the drag strip portion of the test with the TiForce Titanium Full Exhaust and made five passes before it was removed and testing on each of the subsequent exhaust systems in a similar manner was performed. This allowed Lee enough passes with each exhaust to ensure that he had achieved the very best time possible. After each exhaust had cycled on and off the bike Shierts and Russell reinstalled the TiForce one more time to double check that to make sure the original times from the first rounds could be duplicated at the end of the test. This would eliminate any concern that, after 41 hard drag launches, the clutch or other components had suffered any appreciable loss in performance that might skew the results for the systems tested later in the weekend. The bike ran just as fast with the TiForce system at the end of the test as it did in the beginning, making us confident that the test results for all seven systems were representative.