warranty=bleh

Ok, what else can I do (performance-wise) with out kill the warranty on important parts of the car (engine,tranny). The dealer said if i got headers (the ones they sell at the dealer!) and I over-rev the engine, I am at fault. So that doesn't sound too good.

This is what I got so far:

CAI
iridium plugs
high perf. plug wires
high flow cat (in the mail)

I'm considering a turbo (in about 4.5 more years) and from what I have heard, NO2 is not the best.

I'm assuming new cams and cam gear will also kill my warranty. Can I up the compression on the engine a little bit somehow?

I'm not really considering an exhaust because I don't want my car to sound like a bug (and the chrome ones with huge tips are ugly). Any non-chomed, good power producing exhausts?

Also, the air filter on my intake is pretty damn small. Would it make a noticable diff if I got a bigger one or a K&N?

Any suggestions?