So after installing my pacesetter lt headers, texas speed rumbler x true duals exhaust, and dynomax bullets my car sounds like its backfiring when shifting from wot...any idea what can be causing this and how to fix it?

I have an 01 a4 ws6 and everything else is stock.

thanks!

 

Has it been tuned for the long tubes? If it hasn't that could very well be the problem, that and the dynomax bullets offer little backpressure, so it'll make more popping noises than a normal muffler would.