I purchased the 64.5 mm TB from OEM earlier this month. We also bored the stock DE MAF to around 54mm.
My car is a dedicated road race car only. Stock VE bottom end. The head has been cleaned up, match ported and a 5 angle valve job. 3" exhaust turned to the side with a gen 6 header. Calum RT, N-1 cams and 100 oct race fuel. The car has been on several dynos but never the same. It has ranged from 189 to 203whp on stock cams. I installed the N-1's and ran a few races including the convention in Ga. untuned. The car ran well and was not leaning out.
Now I installed the OEM TB and bored MAF. and tuned. After goung back a second time, after extensive tuning. I gained 10whp above 6800 rpm but lost 5ftlb torque.
Here is the thred of the first time.
http://www.sr20-forum.com/vvl/21978-some-ve-noise.html
Gentlemen this is a race car. PLEASE do not ask me what the final #"s are. You just got to come to Sebring next weekend to find out how the car runs.
Thanks,
Andy R.