So i have the 4.2 a6 I want to get nos im putting cat back exhaust and put a tune to it too. So do you think it can handle the NOS?

 

People have used 50-75hp shots on a 2.8 v6 so the 4.2 should be able to do 75-100hp shot. Just don't get greedy and make sure you have enough fuel (wet or direct port and inline fuel pump). I'd stick in the 50-75 range. Better to be conservative.

 

Ok sounds good to me thanks.