Literally man tune is the only thing I've heard of that makes a respectable difference. Even then it's nothing like tuning a turbo car.. If I were you I'd save the coin, like I said I've done it before and it just makes f*ck all difference and you'll get your next car (turbo or v8) and be like... Why the hell did I bother with that I did full exhaust ie extractors, cat, cat back and also the intake. You'll still get destroyed by v8s, turbos etc