i am wondering the same, but whilst loking on ebay the other day i came accross this A4 for sale with a chip fitted:
eBay.co.uk: 1998 AUDI A4 2.8 QUATTRO Tiptronic, SWAP WINK WINK! (item 140109454217 end time 27-Apr-07 20:44:04 BST)
with this comment:
Engine Remapped from 193hp to 210hp £350 at ChippedUK 04/01/07 – Amazing difference.
so he claims an extra 17bhp, nearly 10% extra
thats very good for a normally aspirated engine
btw, you never chose the wrong car
) the 1.8t has a top speed of around 140mph or 225kph and 0-100kph in 8.9 secs
where we can go to 155mph or 250kph and 0-100kph in 7.6 secs
hopefully i dont spark a big debate, but thats what it says on the internet