Intake tube diameter for custome Intake Manifold?

[Chuckcruzin1986]

Hello,
I am working on a custom intake manifold for my 325i stock engine except for a little porting.
The runners length will be about 10" each, go into a common air box, have a throttle body and a 2.7" (maybe 3") MAF and maybe controlled by a Miller set-up.

Any recommendations to the runner tube diameter?

Due to constrictions, the runner length is on the short side so I am looking for high rev power.

I am planning at this point to move the injectors 1 or 2 inches up stream from the head's port.

Thanks for any ideas and help
Chuck

[nando]

whatever you do, don't go too big. dbilas ITBs are 45 and 48mm which is ginourmous, even for a built engine. I'd be looking at 35-38mm at the most. What's the stock diameter? ~30mm?