I am kicking around the idea of eliminating both mufflers on my 98 V70 AWD and having it exit on the left instead of the right. Option #2 is to get a welded race muffler w/ 2.5" inlet/outlet on the left, instead of the right. ANyone running either of these setups with the stock piping? 2.5" piping (stock) is plenty large to pass much boost on a street car.

 

Depends on emssion and where you live. If you need emission...geta race cat.
I would do a 3" downpipe with 2.5" pipe to a free flowing muffler like magna flow.
If you raise the boost abit...then I would to 3" all the way back.
It will get LOUDer with only one muffler though.

 

emissions is not an issue here, boost is going to be increased.

 

+1