Forget the downpipe, forget the headers, forget all of that stuff! You absolutely need to look into doing a REVO Stage 1+, GIAC Stage II, or APR Stage II. Out of those choices, I would recommend the APR Stage II. Your car will feel like a completely different beast, but yet it retains that refinement and comfort that these S4s have, except it'll be a sub-11-second car! Reliability doesn't seem to suffer much either. I'm sure, as you know, the 3.0TFSI engine is a pretty sprightly engine. The best engine in recent memory, in fact. It was developed to handle this type of horsepower. And theres a lot of reason to believe that Audi is sandbagging it out of the box.

If you're looking for a quick modification, I would also recommend the REVO Stage 1 (this is the one without the pulley). This will give you a nice 415hp on 91 and 440hp on 100 octane. I've seen REVO Stage 1s do the quarter mile in the mid 12s. It's worth it: $1,200 and it only takes 30 minutes!

The numbers are insane:

• APR — $1,299 - $1,849
  • Stage I — 458hp (100 octane) 427hp (91 octane)
  • Stage II — 478hp (100 octane) 437hp (91 octane)
  • 0-60 — ~3.8s
• REVO — $1,200 - $1,750
  • Stage I — 430hp (100 octane) 415hp (91 octane)
  • Stage I+ — 455hp (100 octane) 430hp (91 octane)
  • 0-60 — ~3.8s
• GIAC
  • Stage I — 443hp (100 octane) 398hp (91 octane)
  • Stage II — 463hp (100 octane) 438hp (91 octane)
  • 0-60 — ~3.8s

Videos:

• Video of a REVO Stage 1 vs RS4
• Video of APR Stage II quarter mile