How u doin Chris, welcome to the forum!
Used to have a few vauxhall's myself before moving to the wonderfull world of VAG.
Have never looked back since then. Im gussing your A4 Quattro in a 1.8 20Vt?
If so it's such a sweet engine. Strong as an Ox, reliable (jamie wouldn't agree) and very tuneable. Not to mention pretty good on fuel (for the performance anyway).
If you haven't already parted with your cash chek the site, and other forums for some things you need to be checking before buying (waterpump, turbo, clutch, coil packs, timing belt etc).
If you need any info about any diy work there are loads of how too guides.
Now all you need to do is plan some mods, a nice remap, air filter or induction kit, dump valve and exhaust [

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Steve