I already have a 4'' piping that sucks air from the fender (cold air setup) on my GT30R for years now but I would like to regain some space in front of the radiator so I was wondering if a 3'' intake piping (pre turbo) would be bad performance wise for a 4" turbo intake? The car makes 420whp at 18psi and will never boost more then that. Thanks for your time!

 

You have the 4" anti-surge compressor cover. The outside 1" is for the anti-surge ports. The intake diameter is truly only 3". So if you wanted to run a 3" intake pipe with a reducer to 4" coupler that would work just as good.

 

ok thanks for the advice sir

 

post pics of your current setup, sounds interesting

 

Hum, I don't have pics but I can tell you a bit about the setup, I still have the AC and PS, my wastegate dump in the exhaust, I have a metal cat. It's quite busy up front with a full size rad! so If I can use a smaller pre turbo tube i'll be happy to gain that space, and I want to use a pre-turbo slash cut vacuum tube to vent my oil catch canister... so someday when this will be done, my car will finally smells good