The B5 S4 is the most tuneable Audi S4 ever made. The V8 S4 of today may be faster stock to stock, however with a chip and exhaust and some suspension tweaks, the B5 S4 can easily out perform the B6 and B7 S4. The following is the upgrade path I chose in modding my B5 S4.
- Modified intake (this is an easy DIY. Search it on any audi forum. Basically, you just drill holes in the bottom of your intake box)
- APR Chip. As far as power goes this is where I felt the most improvement. Simply put, its whole different animal!!! (I chose this chip over the GIAC chip because the GIAC chip is more exspensive and tends to wear out the KO3 turbos quicker. However, I do believe the APR is more smooth in the power delivery and the GIAC chip is more agressive in its tune, and therefore slightly more powerful)
- AWE down pipes (the most expensive mod I have ever done. And yes, it is worth it, I noticed a big difference in spool up and from my butt dyno)
- H&R coilovers (Dropped the car, closed the wheel gaps and made the car look AMAZING! The handling significantly improved.)
- Rear sway bar (I have not yet installed the rear sway, I am waiting until winter is over and my garage is above freezing =)
Things you should consider buying before following my upgrade path:
- AWE center boost gauge (this will let you know if you have a boost leak which can cause some serious problems. I'll probably be kicking my self later for not installing one.)
- Short shifter kit (The shifting never really bothered me but I will change it eventually. Be sure if you plan on purchasing one to get the kit for your model year, as I believe the shifting linkage changed from 2000 to 2001.5)
- An auto warranty. It would have saved my folks a bunch of money :) It does cost a lot of money to maintain these cars. I recomend SmartAutowarranty.com They will give you a free quote so it is worth a shot. For more info on saving money on car repairs go here!
- I would also recomend a seperate set of snow tires and wheels so you can protect the stock avus wheels and have quality summer tires on them. Shop for Tire & Wheel Packages at The Tire rack.