I druve my friend's turbocharged A4 yesterday, and it performed well if you eased into the throttle, but if you rapidly hit the gas, the fucking thing bucked so bad most of my drink ended up on the dash. I had a first-generation Mazda RX7 that had this problem, and it was obviously old vacuum lines controlling the ignition advance. Could this be the problem? It would be great to only have to replace vacuum lines.