some basic question
The best advice one can give here is that you should be prepared to fix things. Once you start modding, things will break eventually. always have some money set aside and be prepared for the worst.
For the record, i am still running the stock 6 speed. I have some hard launches on the bottle. see sig for numbers. I have money set aside for a fix and i am fully aware that i am on borrowed time. As far as the rear end goes, my stocker gave out within a month of my h/c going on. And this was with stock tires!
Good luck.
M6: More involving/funner to drive, requires more skill to get good with, better from a roll, better gas mileage on the interstate.
A4: Awsome from a dig when you get a converter, easier on the rear, less likely to have been beat on in terms of buying a used car.

