The customizing covers quite a bit and a lot of good stuff like diy jobs, etc. I’ll post up more info about it along with the pictures later tonight. I’ll also see if the Haynes manual has the S4 in it, from what I remember it didn’t but I will double check for you.
VW Passat 1998-2005, Audi A4 1996-2001 Repair Manual | Haynes just googled it.
No it doesn’t cover the S4
This repair manual covers Volkswagen (VW) Passat, 1998 through 2001, and Audi A4, 1996 through 2001. 1.8L four-cylinder turbo and 2.8L V6 engines. Note: this manual does not include diesel engine or S4 model info.