Look out for rotten/split hoses as there prone to failing and causing idling issues and boost leaks, but this is only due to their age.
My PCV system had to replaced as the oil had rotted most of the bends, easy to replace with a Oil Catch Can.
think your year comes with the secondary air injection which pumps air from the air box to the exhaust, some thing to do with helping the cats to warm up so don't worry if there's a whirring noise coming from under the inlet mani.
Gearbox shouldn't crunch and controvert to popular belief the S3 isint a full time quattro, its uses a Haldex coupling (viscous Diff) to vary the power transfer to the rear diff. Most of the time its 90/10 torque split to the front wheels and will only operate the coupling when the front wheels spin faster then the rear, unless your like me and get a Haldex Blue controller to make the Haldex active on full throttle, But Haldex don't make the Gen1 controllers any more so you`ll have to wait patiently on fle bay.
So with that look for Haldex oil and filter replacements in the invoices of the service history, New oil @ 20K and oil and filter @ 40K.
The front wings are bad for rust, look under the fold of the wing. I payed for genuine wings from Audi as their anti perforation warranty is not worth the paper its printed on.
The lower door blades hide rust that will creep out over time, they vibrate and rub through the paint and galvonise and road ****e collects there and will rust away and the mounts that the blade sits on will simply dissolve away, again it came out my pocket to repair.
Oh and look for smoke on start up and when giving it the shoe.
Hope this helps
Happy Motoring
