I am thinking about purchasing either a new A5 or S5. Of course, like every car I have owned, it needs to be modified.

So far, I am looking at Stasis and ABT for tuning needs. (suspension and exhaust etc...)

You guys have any other suggestions? Any help would be appreciated.

 

Well I can assure you that the 4.2L V8 in the S5 is remarkable. It will need an exhaust and a chip (well, reflash) never hurts. Other than that, short of the superchargers that are a small fortune there isn't a whole lot to do. The intakes on the market have been few and far between and they never manage to show consistent gains over the factory systems.
Stasis makes some killer setups with Ohlins to get the understeer and body roll dialed out.

The V-6 is everything that the V8 is, minus the fun... (Hahaha, so I'm a little biased)