A guy in the maintenance shop at work can build me a cold air intake out of the stainless materials they have laying around. I measured the pipe at 3" ID, and he will butt weld 3" 90 elbows on. Do you think 3" allows enough airflow? I could go up to 4", but it would neck down to the 3" MAF anyway.

 

Well, as long as it is bigger than your TB I believe you should be fine. 3 inch is much bigger in area.

 

Actually, the twin 58 mm bores would be a little bigger.

 

yeah, but since the 58mm is too big I think you will be fine with a 3 in. Also remember that inside the TB when it is open are the throttle plates which reduce area and cause some sort of turbulence.

 

Due to the neck at the MAF (like you mentioned) 3" is fine and will induce less turbulence.