Perfect Diameter Exhaust Piping size?

[InfamousEclipse]

I plan to turbo my engine, anbd dont want to drop $500 on an exhaust, I have to end up replacing. My question is, what size piping is good enough for a turbo, but not too wide for a non turbo? 2.5? 3? or will piping that large hurt the performance on my RS? Till I turbo it? (it's going to take about a yr)

 

[DSM-ZERO]

2.5 is good for non turbo and still good for turbo but if you want to turn up the boost later on you might want to consider a 3.0 for turbo it will flow more air and help spool the turbo faster by lowering back pressure even more, but if you go 3.0 on a non-turbo yes you will hurt your preformance because you won't have enough backpressure for your motor. If you just want to run high boost later on just get a 3.0 I had my gst tanabe racing medaillion before I had turbo and I lost about 3 tenths off my 1/4 mile time but when I went turbo it was worth it and yes a gst exhaust will fit on a RS/GS.

 

[mike250]

the cheapest way is to throw a gst muffler on..it will fit, then when you go turbo put the 3" system on