I recently purchased a 95 Z28 with 80,000 mile.The only thing done to it is th owner had the muffler replaced witha straight pipe.My questions are,I am changing to a 3.73 rear and am curios of the difference in acceleration and 1/4 mile.What type of effect will this have on my in town/highway driving?What will this do to my gas milage?The car is also a A4.thanks.

 

assuming your car has 2.73's, it will change the acceleration of the car drastically, but you will lost some top end (so what). its completely worth it. you will lose some gas mileage in town, but you will see most of your drop on highway crusies. the a4 overdrive is only .70, so if you will run a significant number higher rpm on the highway. for cars without 11 second timeslips, 3.42's seem to be a good choice. you dont lose as much top end, and it will still be a vast improvement from 2.73's. if you have 3.23's (varified by a "1" on the shifter plate below the "2") and you are unhapy with them, you might want to go with 3.73's. personally, i like gas mileage, and it's not worth it to go to 3.73's over 3.42's on a bolt on A4 car IMO.

 

How much of a e.t. reduction can be expected with the gear swap,cai, and catback?Would 4.10s be overkill on the A4 car?