I have a 370 Z coup and I want to increase the power, how can I do that and not void my waranty?

I have the same question... I think the easiest way is to change headers, cats, and exhaust. My question is what brand will give the most for your dollars?!!

There are many ways to improve power via simple bolt ons. As far as keeping your warranty in tact, that is another question. Usually something like the addition of a cat back exhaust or intakes won't really affect anything when you go in for any kind of regular maintanence, something like an aftermarket clutch might.

If you're looking for power, the easiest way is to free up the airflow so to speak. Companies like Berk and Stillen make some good products but the choices nowadays are endless. I would start with intakes, high flow cats and exhaust. A tune wouldn't hurt either. From there you can start tinkering with other things to squeeze just a bit more power out like say, a lightweight flywheel which will yield about an added 5 whp.