Are the Corsa DB black mufflers decent? I also don't see a center inlet and center outlet but I see some people have used these. I don't need a whole system and I can't seem to find a Corsa Sport someone is willing to sell. The 2.50 inlet/outlet bothers me a little but if it's free flowing more than the stock muffler I think it may be ok. What do you think? worth it? Their about $170.00 for the muffler.