Is a 3.5" downpipe enough?
What about the exhaust,3,5 " or 4" ?
Thanks in advance

 

If you have to ask, it's probably enough. How much whp will you be putting down? If you're under 500 whp, then 3.5" is enough. If you plan to max out that t-88 and have the supporting mods to boost, then I'd go 4". Some people draw the line elsewhere, but this is what I learned. I had this question myself a while back and I called a respected rotary tuner and asked.

 

4" from turbo to the back !!! **** even better get an elcetric cut out valve and run a dump pipe(or side exit exhaust) right off the down pipe ....... scare the **** out of everyone and spool up crazy quick ,....you can build your self one for like 220... electric valve3.5 and dumpipe from jegs ....