Get a set of gears if you haven't upgraded yet. I'd recomend 3.73's. After that try the 65mm TB and see how it feels. If your car feels stronger in the upper RPMs with the smaller TB now, gears would let your car get out of the lower RPM range better, and the larger TB might help it climb better than your current 60mm once it did.
I have a setup somewhat similar to yours...
• K&N air filter
• MAC cold air kit
• 76mm C&L MAF
• 70mm Accufab TB and EGR spacer
• GT-40 intake
• 1" Phenolic spacer
• Walbo 190lph fuel pump
• 24lb SVO injectors
• Kirban adjustable FPR
• Ported stock E7 heads - 3 angle valve job - shaved .030
• Omega 1.6 roller rockers
• Crane valve springs
• F303 cam
• MAC 1 5/8" long tube headers
• MAC 2 1/2" Pro Chamber
• MAC 2 1/2" cat back with chrome tips
• MSD Blaster coil
• FMS 3.73 gears
• MAC under drive pullies
My car has the power right where I want it with this 70mm TB. It is still torquey down low and shreds pavement from mid range on up. At times it has even caught me off guard when I hit 3rd gear coming out of a corner and the car decides to go sideways on me. Your gears and the weight of your car is killing you, and a 65mm TB shouldn't hurt your cars performance I wouldn't think since my 70mm works fine for me. LS1's and the new GTs get left behind me at the lights
------------------
Gunning for 12's!
Buy your parts here
ICQ# 42269241