[Oldsman]

i would go with one pipe. reason being that at the point of the Y you will create a turblence and could increase backpressure. by how much not sure. but a turbo setup doesn't want backpressure being this increases turbo lag to a degree.

I have talked to a good friend that has a 10sec GN and has own a few other10-11 sec buicksover 7 years and he has gave me some good info. so this is where i get my info from.