Ok so apparently my last post was confusing some people so i'll just repost on the most concerning issue.

A few people have mentioned the rattling can sound I hear at 5k+ rpms under load is detonation (sounds so comforting ). I'll try to put a video up but I dunno if my camera will be able to pick up the sound very well.

So if it is detonation, engine knock, or whatever and I've always been using the proper fuel... how do I fix this?

It pisses me off that I didnt take care of this while it was still under warranty. I thought it was somthing with the exaust cuz thats what it sounded like. Figured it was gonna be fixed anyway when I replaced every bit of the exaust.

'02 SS A4 ~48k miles. no serious mods.