hey, im doing a im putting a turbo in my gslse and i dont know for sure how big of intercooling pipe ill will go. im using a stock S4 turbo, S4 tII manifold, and a NPR intercooler. the turbo and the TB plate is 2" but the NPR intercooler is 2.5".what to have boost drop either. what should i use 2", 2.25" or 2.5"? thanks

 

With that turbo I'd recommend 2 1/2 from the turbo to the IC and then from the IC to the TB...You could try an NA elbow from an 86-91...I don't know if that will fit a GSL........

 

i try already, the oil filler is in the way.

 

I used 2". I didn't want to go any larger with the stock turbo due to lag.