To illustrate this point, we called on Thermal Research & Development out of Canoga Park, Calif. The company has realized a need for performance turbo exhaust systems for Hondas and Acuras, and has been working closely with top import racers to design and develop the perfect exhaust system for both the street and the strip. Extensive R&D efforts have resulted in the development of a complete line of 3-inch mandrel-bent, stainless-steel exhaust systems specifically for turbocharged Honda powerplants. By effectively sizing the piping diameter and muffler flow characteristics, the Thermal system allows the engine to produce its full potential. Thermal offers both 2 1/4-inch and 3-inch exhaust systems for both normally aspirated and turbo engines. The 2 1/4-inch system is a bolt-on affair and does not require any modifications, but the 3-inch system requires the mounting of an extra 3-inch flange to the catalytic converter.

Our tester was a newly rebuilt 1990 Acura Integra LS utilizing a custom XS Engineering turbocharger and front-mount intercooler. The engine has been fortified with 9.0:1 JE pistons and Saenz rods. The engine still utilizes the stock head and cams, and currently runs an upgraded in-tank fuel pump and boost-dependent regulator for fuel enrichment. Our baseline run at 7.0 psi of boost running the normally aspirated Thermal 2 1/4-inch exhaust system registered 189.6 hp and 165.9 lbs-ft of torque. By just bolting the Thermal 3-inch exhaust system in place, we were able to increase peak horsepower power output by 2.2 and peak torque by 2.4 lbs-ft without touching the boost controller. Peak power now checked in at 191.8 hp and 168.3 lbs-ft of torque. We were also able to see an increase in power output throughout the entire powerband with jumps of 4-5 hp. Overall, we were happy with the increase generated by simply swapping exhaust systems. We are positive that when boost pressure is turned up, there will be a more significant increase in power with the larger diameter exhaust system. We are planning to re-test the exhaust systems when we upgrade the head and cams and increase boost pressure.

Having a plan of attack is the best way to prevent excess spending. By determining which performance route you plan to take, whether it is normally aspirated or forced induction, it is wise to purchase the right exhaust for your needs the first time. And thanks to Thermal Research & Development, you can plan to boost to stratospheric levels and still have a system that muffles and allows the realization of maximum power.