Sorry brother, but it's absolutely not the heat shields. It's the AA EL midpipe, itself. Check out this thread where people who buy the midpipe become salespeople for it, even though they know it turns your car into a straight piped civic. And they delude themselves into thinking it was worth the investment even though we all know it sounds like a straight piped civic.
https://f80.bimmerpost.com/forums/sh....php?t=1893796