Intercooler pipe diameter questions

[Bdubs]

Ok here is the setup right now, redtop sr in an s14. I have a spearco bar and plate front mount with 3" outlets. I havent piped it yet, but here is my question, what size pipeing should i use. I am think a 3" on the intake side/ cold side, but what size is the stock throttle body? I am sure i will have to run a reducer. The on the hot side im not sure at all what size to run. I am think 2.5" and run reducers to the intercooler and turbo, but what makes the most sense? Thanks for any inputs and ideas, and fabrication is no proublem at all. ( intercooler size is 24X12X3 )
-B

[Bdubs]

and unfortunatly at this time i am still on the stock turbo, forgot to mention that part.

[llteddy4playll]

I would just do 2.5" cold and hot side unless your car is going 500 hp or so. But people usually do 2.5 hot and 2.25 cold.

[Bdubs]

It will have around 400 with the gt3037 i am putting on later this summer. And I think i am going to end up going with 2.5 all the way around. No sense to run a quater inch smaller on the cold side, and 2.5 on the hot. 2.5 in with some reducers will have to do the trick.

[WeldingHank]

2.5" on both sides would be perfect for 400HP

[Flybert]

I would just do 2.5" cold and hot side unless your car is going 500 hp or so. But people usually do 2.5 hot and 2.25 cold.

Completely wrong. Premade intercooler setups from japan usually come with 2.25" on the hot side and 2.5" on the cold side.

Personally, if I was going to be making about 400hp, I'd upgrade that puny S14 SR throttlebody and run the same size TB diameter as your cold pipe. As for the hot side, I'd go with 2.5" with that kind of power.