pick the exhaust you like best
http://www.rs25.com/forums/showthread.php?t=52687
first things first. get borla/borla replica's (ebay) for the suby rumble.
go catless if you want a really good power gain
when even you put a new exhaust part on. you should always get new gaskets. but i play it by hear, if they look good than reuse them. but others will say different. i just use it until it leaks...lol
i love the look of the greddy EVO 2. but if u go catless make sure you have a nice long resonator in the midpipe to cut on the raspyness. if u want to just want to get a small gain in HP and sound. get a greddy evo 2 axle back or catback if u perfer or depending on the price you find. and get the headers i said above.
there is a TON of info about people asking the same questions. im not tell you to search but reading what others said might add on to something i said or you might find something else you i didnt say or what others didnt say.
let me know if you have any new question
oh...BTW... going catless will make you get a CEL, use a spacer to get rid of it, and going catless will make you fail emissions. so KEEP your stock cat and just bolt it back up when emissions com around
