Hi, I've

RE: 2000-2002 S4 Airbag Question - differences between those years? (also S4 Stage 3 question)
 

Welcome to the board!

The 2000-2002 S4s are part of the B5 platform, we refer to those years as the B5 S4s. Airbags in the B5 should be the same across all years.

With regard to your question regarding Stage 3 2000 vs 01.5+, definitely look into who installed the turbos/fueling, see if you can get a receipt or some confirmation of the parts and labor involved. Going stage 3 is a pretty big job, youll want to make sure it was done right. The oil lines should have been replaced, hopefully with a set of larger upgraded braided steel lines, double check this and make sure. All other plumbing for the turbos should have been changed to RS4 components as well.

There is one key difference between the 2000 vs 01+ which is the Electronic Stability Program or ESP. ESP wasnt put into place until 2001 and later. This cuts power to the wheels and applies the brake in an attempt to recover control of the vehicle when you loose traction. Most people dont care about it, depending on where you live. If you live someplace where it snows or gets icy, you might want to consider getting an 01 or later since it will be pretty easy for the tires to break free when youre running ~400whp. There is a button to disable ESP for those times when you need to haul a$$.

Youll also notice the badging on the front/rear/steering wheel/instrument cluster will be the newer S4 logo starting in 01.5. Aside from that, the different B5 years are the same.