3" exhaust, and a nice turbo would help. Lol. Precision makes a pretty sweet 50 trim, the 5431 CEA, good for 4 cylinder cars. That's what I'm running right now on my sentra, 2.5L. I'm at full boost (9psi) by about 3.3krpm. and making 288whp on 2.5" and 308 on 3"