any down sides to getting a tb that big with the mods in my sig??? Eventually I am going to get a 347 stroker with a trickflow top end, and possibly a s/c! But it will be a while b4 I get that stuff. I dont want to buy a 65mm and then have to buy a bigger one later.
When i measured my manifold opening, mine is 72.8 mm across it.... i dont know if all manifolds are that, but mine was bigger than 70, so i went with a bigger than 70mm TB
i had a 75 and i ditched it in favor of a 65mm. I have HCI Trick flows R Intake which is 75 mm opening but as far as drivability 65 seems to work great.
with your combo the stock one would hold you back. IMO if you still have stock heads n/a stock tb is the best choice. i never measured so i cant say for sure but the stock gt manifold is going to be smaller than the cobra.
When i measured my manifold opening, mine is 72.8 mm across it.... i dont know if all manifolds are that, but mine was bigger than 70, so i went with a bigger than 70mm TB