Has anyone ever done this and would it be beneficial?
 
I am upgrading to a air to water cooler kit and the intercooler has a 3 inch outlet.  Would anyone recommend what I should do?
 
I am thinking about using silicon reducers and either:
- reduce the piping size at the cooler to 2.25/2.5 (which means run 2.25/2.5 inch pipes from the cooler to the turbo and throttle body) or
- reduce the piping size at the throttle body and turbo instead. (which means run 3 inch pipes from the cooler to the turbo and throttle body)
 
Does anyone have any thoughts on this?
 
Cheers
 
C Jay

I used 3" piping on mine and just the reducer at the throttle body.

Some will say there is no point in using anything larger than the throttle body, but I doubt there is much/any difference.

Just go with what you think looks best.

I think there is a point in running piping larger than the TB if the IC pipes are press bent (ie. not mandrel).

You will lose around 1psi pressure at the manifold (and to an extent some VE) by increasing the size of the piping to 3" all throughout the system.  Unless you have an intercooler system with 3" inlet/outlet, you are just adding turbulence to the system, as the air has to compress and then expand once it leaves the IC, then compress again at the throttle body.  I had better response using 2.5" piping with my EMS Intercooler as it left everything consistent right from the turbo itself.

Bigger before the cooler is ok, but after its gone past the cooler the air is denser so needs lesser space so you can have a smaller Diameter piping if you want to.

Also larger piping has a bigger surface area, so your cold pipe will heat up slightly more :D
I don't think there's a hard and fast rule here. So long as its not the bottleneck in the system, the size shouldn't matter too much. I'd minimise the number of reducers/expanders, then take available space into account. Going slightly bigger on the hot side is generally okay too.

Thanks guys!