Racer78,
This wouldn't post on your open letter so I'm sticking it in here.
I can only speak for myself as to why there is little discussion going on with the C5 owners, at least this one. First off it took awhile to get over the shear power and the way it put it on the road, even at top end, and I've been close. I liked my C4, '92, but there was just no comparison, plus comfort.
After a couple of years I did go to the Corsa Indy, K&N filter, knocked out the screen in the intake, lowered it about an inch, and went to 17” wheels in the back. What it has done for the power is only a guess, I’ve never had it dyno’d. I have the A4 with the 3.15 gears and was looking for a better launch and lower center of gravity for autocross. I only run the 17’s for 2 days, nothing would hook up to my liking, plus I didn’t have the time to get used to it, burnouts were awesome, handling was off a bit. Off come the 17’s, which were EMTs, the tire swapping thing can get expensive out here, closest shop that can change them is 60 miles away. I do plan on changing the flow in the “X” pipe this winter, more for the sound than power, the Corsa sound too much like a boat.
Right now it is just one driving pleasure to get in it and cruse, will try the autocross again next year.