[submariner409]

The upper RPM is permanently redlined by the PCM. 6250 is IT. Period. After the larger intake work, a lower restriction (there isn't much, stock) exhaust much larger than 2.75" will further decrease low end torque and slightly increase WOT redline power, but see above for electronically limited redlines, or would you like to see one of three timing chains break and go snaking around inside the timing case?????? (And this is an interference engine: a timing chain breaks, the valves hit the pistons, and instant junk.) I am a fan of CORSA, because I own one of their systems (Disclaimer.....), it's pricey, but when you can lift the car, remove the stock system, and install an entire cat-back in less than 45 minutes, and it's guaranteed for life and does have some top-end power gains while not droning you out of the car, what's the drawback??? The OEM cat is not a significant restriction problem, either.