I know SLP recomends running a 1"5/8 on the 305 and 1"3/4 on the 350. What if you put the 1"3/4 on 305? How much of a difference would it be, and would it be better than running stock exhaust manifolds. I know its an awefull lot of exhaust flow for a 305 and may decrease the low end torque. What are your guys thought about it. Let me know.

THANKS

 

it beats the hell out of a log style exhaust manifold.

Just my 2 cents

 

im not sure if 1 3/4" is too big for the exhaust port or not, if it is then i dont think it would be good to step up that large, im pretty sure if the tubes are too big, the gas coming out of the exhaust port has room to expand and looses velocity, which is not good, this causes a decrease in power(if this is wrong please forgive me, im still trying to learn everything). so if they are too big stick with the 1 5/8"

 

I figured they may be to big. But I was able to pick them up for real cheap, but i also plan on running a 350 in the near future. Are they still going tao be better than stock if i put them on now and not wait to put the 350 in? Is it going to be ok since the Y pipe outlet is 2.5", I have heard that if you want to make a 305 better is to just put headers on with a 2.5" outlet to cat from the Y pipe and than go to a 3" cat back.

 

If you already have them, use 'em. They'll be fine. They are not optimal for your 305, but if you are planning a 350 upgrade in the future, there is no need buying header just for the 305 when the 1-3/4" 's will work until then.

Regardless, they will be much better than you stock manifolds. You exhaust tone will be better too. If you are sure you will do the 350 swap, go ahead and run the exhaust as if you had the 350. There's no need in spending money twice.

Good luck.

 

most TPI 350s dont need 1 3/4 primaries either. I think John Lingenfelter uses stock corvette manifolds or 1 5/8 headers on engines up to 400hp

 

It will be fine and you will gain power all threw the power band.