[adriano_917]

what size 65,70,75 of throttle body should i use on my stock manifold and what brand would be better ??? i heard that 75mm is to much for a stock upper(manifold) and lower intake

[GTRaptor]

Well, the problem is the stock manifold entrance is only 60mm, so what you need to do, no matter what TB you use, is port-match the intake to the TB size.

A 70mm TB will be fine but it think it is a waste unless you upgrade the intake or port it (not only match it but port the hell out of it).

Save that money to buy the intake, it is worth more HP even with the stock TB.

[adriano_917]

what do you mean by match it and port it ??? is it better to buy another bigger manifold like for example a edelbrock performer...

[GTRaptor]

Port matching means you need to enlarge the intake port to the same size of the TB.
If you dont there will be a "step" between TB and intake, that will restrict flow, and hurt performance.

On average a decent manifold is good for around 30+HP or more depending on your mods, a TB is at the most good for 10hp.