I am looking at upgrading my exhaust. I already have a 4" set up from the resonator back (muffler and tailpipe) and have a 4" downpipe lying around. It wouldn't be much to gather another section of 4" pipe and weld it all together. I am also planning on upgrading injectors and turbo(s) at a later date, but want to do the exhaust once. Will the 4" suffice or dose anyone recommend the 5"?

 

4in will be just fine

 

4" is fine, but I wait until after you did the turbo. Honestly, how much benefit can enlarging the 3.5" be when the turbo charger is more like a 2.5" pipe?

Your turbo is far more restrictive than the factory exhaust, so I think a turbo is money better spent-- jmo

JΩ$TIN

 

I have the 5" silverline, and I love it (the sound). However there is very little room between the downpipe and framerail. Sometimes it vibrates against it and drives me crazy. I would do 4" next time.

02 2500 4x4