How to Upgrade your Syclone’s Exhaust

Sport Truck Annual

Syclone Exhaust

GMC’s Syclone pickup is a formidable performer straight off the showroom floor, but as is the case with any factory vehicle, there’s always room for improvement. However, given the current state of emissions laws, legal modifications are limited. Among the most popular mods is the installation of a less-restrictive exhaust system behind the stock catalytic converter. These systems unleash a few extra ponies and dramatically improve performance and even mileage in some cases.

Borla Industries was recently tapped to develop a catback system for the Syclone for SCCA’s street truck racing series. Its objective was to allow exhaust gases to exit the system more quickly and reduce power-robbing bends in the system. The result of its efforts was a bolt-on, smog-legal, stainless-steel system that boosted power and performance. The Borla system is constructed of T-304 aircraft-quality stainless-steel material for the muffler and mandrel-bent pipes ( l 8-gauge/.049-wall thickness). It also utilizes a single 3- inch pipe from the catalytic converter to the muffler in place of the flow-restrictive factory Y-pipe, which splits the exhaust into two mufflers. Use of the 3-inch behind the catalytic converter allows for the expansion of the exhaust gases due to superheating at the converter while reducing backpressure at the same time.

Another significant difference between the Borla system and stock setup is muffler design. The two stock Turbo mufflers use reversion (bouncing the exhaust gases off of baffles) to deaden the sound, while the single Borla muffler traps sound as heat energy through absorption in the synthetic packing material. The Borla unit also features a larger inlet pipe (3 inches) and twin 2½-inch outlets for a less restrictive exhaust flow.

Installation is a simple R&R operation-remove the stock pipes and muffler and holt up the Borla pieces. Ed Bales at R&E Racing performed the installation on our test-mule Syclone in less than an hour. Then it was off to Los Angeles County Raceway for some testing. (Dyno testings on a Syclone is out of the question due to the fact that it’s all-wheel drive.) Pro hotshoe Jim Wheeler of Wheeler Racing did the driving duties on the quarter-mile. All passes were started from idle and made in the Drive position to ensure uniformity in testing.

The results? The best time the truck could muster in stock trim was a 15.78-second pass at 89.l9 mph. With the Borla system installed. the Syclone turned in a best of 15.43 seconds at 91.60 mph. Utilizing the NHRA correction factory for the track’s altitude. the Syclone turned in a 15.53 at 90.71 mph stock and 15.18 at 93.16 with the Borla exhaust. Drivability also improved, according to Wheeler. “The Borla exhaust provided better acceleration off the line. It was actually possible to chirp the tires. and it gave more turbo on the top end.” Despite government regulations. smog-legal performance can be found through the utilization of the proper components, and the Borla stainless cat-hack system for the Syclone is one of them.