i think i should start off with the pop charger then what. pros\cons- test pipes headers, y pipe, test pipes, exsost. and what brands are the best.
i like the sound of the nisimo and i like the proformace of the injen.

 

There is a ton of info on all this if you search or just look through this section of the forum. But i will give some info as well.

I agree and so will many, that a popcharger is one of the best mods for the money. As for the entire exhaust system there are a ton of routes you can go. Alot of people are very happy with the Injen Straight-Tip exhuast, Greddy Evo2, and Borla True Dual, as well as many others. Test pipes/HighFlow cats are a good mod if you do not mind the car being noticably loud w/ some possible rasp.

But like I said, some good searching will answer 99% of your questions you may have.

 

Test pipes are nice, but if you have an '04.5+ model year, expect an SES light. I have posted a couple fixes for them. If you are going unresonated, a testpipe is a testpipe. Get the cheapest ones. Otherwise, good resonated ones are Labree and Kinetix.

In terms of exhaust, if you like the Nismo, get that. The exhausts I like are the Greddy EVO2 and HKS dual TI tip. The greddy sounds much better IMO, but the HKS looks a bit better. I am not a big fan of the injen exhaust.

LINK TO SES SOLUTIONS

 

what is there not to like about the injen system ..sound? price? i thought they had a good hp and wieght

 

I didn't say it wasn't a good exhaust. I just said I don't prefer it. I like the look of the mufflers, but not the tips. I have heard that the insides of the mufflers contents have been reported to shoot out the exhaust, hollowing out the mufflers- can't remember where I heard this, and I think it has been resolved. I have heard that if you run test pipes on it, it is CRAZY loud. Most of this is second hand so it may or may not be true. All I know is that I prefer the sound of the greddy over the injen.