75mm or 78mm throttle body really worth it?

[96z71slt355]

Its winter time again my truck is down for some much needed tlc and a few upgrades. I was wondering if one of those 78 or 75mm tb's would be worth the money? My motor is a 96 vortec 355 with a lunati voodoo cam and true 2.5" duals with no cats. I am thinkin about some long tube headers also and probably get a black bear tune also I just dont want to spend the money on something thats not gonna give me **** in return. Thanks in advance

[chucksrt]

The throttle body opening is the same size as the opening on the vortec intake manifold. I can't see a larger TB doing anything? I got a Tune from PCMforless and they can tune for just about any setup you can throw at them. Long tube headers should help it out a good deal. I wouldn't get a tune until you know exactly what mods you are going to do to it so you don't have to waste time having it tuned again and again!

[Botan]

i installed a 75mm last night, along with a hypertech programmer and i'm pleased with the results. I'm waiting now to see if my fuel mileage increases some as well.

[chucksrt]

I didn't think there was any room to bore the TB? I never measured the manifold opening but when I was doing my rebuild I checked it didn't think there was a difference? 4mm bigger is pretty good and having the restrictor removed should be an improvement in it's self! I may have to think about diong this to hold me off until I do a edelbrock manifold upgrade! I'm guessing you have a lot better throttle response!

[Botan]

I didn't think there was any room to bore the TB? I never measured the manifold opening but when I was doing my rebuild I checked it didn't think there was a difference? 4mm bigger is pretty good and having the restrictor removed should be an improvement in it's self! I may have to think about diong this to hold me off until I do a edelbrock manifold upgrade! I'm guessing you have a lot better throttle response!

the throttle response is awesome. and yes the stock throttle body can be bored out. i think it can go to 80mm max before interfering with the iacv.
i dont know the exact measurement of the stock throttle body, but i put the stock next to the 75mm and could see a difference in size, how much idk. if i get around to it today, ill measure the stock one, i do know that the stock throttle body is smaller than the intake opening tho, because i can see the edge of the intake through the 75mm throttle body, where as i couldn't on the stock.