AMS stopped making any/every exhaust design for the 335i. It wasn't the design, it was more of the fact that they backed out of the N54 platform and the lack of sales for a $1600 exhaust.
Our muffler is actually smaller than most dual exhaust mufflers when combined and it is very free flowing (non-baffled unlike most dual muffler systems). I've heard the HPF and a couple of other "muffler delete" cars and they were way too loud/raspy/droney for my taste, but we do plan on targeting that market
