1991 Nissan 240SX LE - Power Pages

Conclusion
Replacing the downpipe and exhaust on our SR20DET-motivated 240SX reinforced a well-documented truth of import tuning; backpressure is the arch-nemesis of a turbocharged engine. Where the addition of a head-back exhaust system might normally free up to 10 whp in a similarly-powered n/a 2.0L application using a catalyst, the placement of turbo-back components netted a 28 whp improvement in our 7psi-limited instance. Allowing the turbo to boost higher would've shown even more power than could've been possible with the stock system. The addition of the Super Ground Stabilizer proved its worth on the dyno, giving a few additional ponies to disprove long-held claims of "snake-oil" that surround products like it. Most importantly, this month's testing shows the power production benefit of parts that should be added to street-going cars for other reasons: Swapping out restrictive stock exhaust components allows the engine to aspirate easier and the grounding kit frees the electrical system from performance-robbing interference; two modifications that ideally serve to increase overall efficiency, meaning greater fuel economy and longer engine life, as well as increased power production. Eliminating the only remaining source of backpressure in the system, the stock catalyst, would produce even more impressive results, but we wanted this test to show the benefits that can be obtained while adhering to popular emissions and noise regulations. While there's nothing we can do to change laws that restrict the use of certain engines in road-going vehicles, at least we're able to show there's no practical reason for their being.