throttle body size?

I will soon be replacing the throttle body on my B18a, and have been deliberating on whether to go with a 65mm or 68mm. I believe a 70mm or larger throttle body will cause to much of a decrease in air velocity and negate any positive effects. I had decided on a 68mm, but was wondering if any of you had ever tried either a 65 of 68mm and what kind of power gains you got or any weak spots you found in your powerband. compression is stock, timing is stock, and the relevant upgrades (i.e. intake/exhaust sys.) that would affect the proformance of the body are: cold air intake ducted to front bumper, throttle body spacer, 4-2-1 header w/crossover pipe, and custom 2.25" cat back w/flowmaster deltaflow (60 series).

I would go 65mm. Type r tb are 64 and i hear its noticable at that size. I just dont like goin too big. 70mm makes u lose alot of torque. Its mainly for force induction. 68mm is a bit too big. i think 65 is perfect.