Ok everyone i'm sort of new to the whole "mod your car" scene and i was wondering... if you just buy new high-flow cats and headers but don't buy a new cat-back exhaust system, will it still sound a lot better or do you need the full system to make it sound more ferocious? any help or comments are appreciated!

 

if you didnt know by 'it' in the above paragraph i meant WOT engine noise.

 

If the choice is "either-or" on the headers versus the catbacks...get the catbacks. More hp gain, easier to install, better impact on sound.
You will not get the header "growl" of course, but you will get more hp. The RT opens up the sound and richens it.
Be careful about the type of exhaust unit you choose, because some are raspy. The Stillen, Borla, Nismo are all pretty deep, but there are others that have strong and enthusiastic supporters.

The real issue is....will anyone out there disagree that the catbacks should be preferred to the headers if you can only have one or the other?