Got my car "Y" Piped today.
Found a shop and had the guys cut the silencer out and fab up a "Y" using the already in place flanges. $50
(Basically the guy went to a muffler supply or part shop and bought the "Y" while I waited. Came back and then just welded it in place)
The noise diff is negligible. In fact in my own car if someone had done without my knowledge, I'm really not sure I would have / could have been able to tell/notice the change without a heads up. So no real sound difference and as for the Buttdynometer,...cant really tell there either.
Still all in all , I'm glad I did it and I'm glad I went the cheap route. And Since I have an OE 500E Cat back system on my 400E, If I ever want to swap back to silencer mode...no prob.