Aftermarket DP on stock exhaust??

[RicciDSM]

A buddy of mine has an Apexi Downpipe for a FWD DSM that hes willing to give me. I came up with the idea of getting a QTP electric exhaust cutout and welding it to a section of the downpipe and using it with the stock exhaust. That way I can be quiet, or run open downpipe when I want.

Question is, will an aftermarket downpipe bolt up properly with the stock exhaust? Im not sure if the DP is 2.5" or 3" or what, ill have to measure it when I get it. Also would it be better if I put the cutout ON the downpipe, or in the stock exhaust after the DP but before cats etc ect...

Thanks in advance for any replies

 

[LiquidX]

It will bolt up to the stock exhaust and the cut out would be most effective pre cat and closer to the turbo to expel as much exhaust as quickly as possible.

 

[dsmdeliveryboy]

Ya a lot of people run a aftermarket downpipe and cut-out with the stock catback, you might just have to have a different flange welded on your stock exhaust to accept the bigger piping etc.