I was planning on going from the 3.5 turbo outlet up to a 4 maybe even a 4.5 inch downpipe. Been doing some reading on the subject and cant believe the difference the downpipe has made to spool rpm and bhp.
My only problem is going to be there is no way on gods green earth I can get a 4.5 inch pipe past the engine above the front subframe and if I go below il lose it on a speed bump... I have had a slightly mental idea about getting some thick wall 5 inch steel tube and notching the subframe/cross member and replacing the notch with the thick tube (probably makes no sense in my explanation but I know what I mean haha) but wel see. I could do with another subframe to chop about if I'm honest