I was looking at buying the atp downpipe for my car and matching it with the eip tuning muffler. Dont know if i should run it three inches all the way through and sacrifice some low end torque or make it smaller. Or go with the apr exhaust wich is way more money. any input .

 

If your ever gunna go Bt id do 3 but if your not then stick with 2.5 or 2.75

 

quick question...what's Bt?

 

Big turbo, ie GT2871RS and similar