If anyone knows how much horsepower are you expected to gain with the vortec heads??

Where are some other heads and how much horsepower would you get form them?

 

Compared to the stock GM 305 heads I bet you would get a nice 30-40 hp gain provided you have a good flowing manifold. Everyone I've heard that has them heads had a nice seat of the pants difference in hp. If my motor had not had high miles on it I probably would have bought those heads and a manifold that would work with the Vortec bolt pattern instead of just changing my intake. A recent GM High Performance magazine ran a bunch of test on a lot of heads and the Vortecs were rated pretty high and said they were the best bang for the buck but if money is no object I would go with the AFR 190 heads. They are one of the best flowing heads on the market and they are aluminum and don't have to worry about the limitations of manifolds that can be used with them.

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1988 TA 300+hp 350 w/ TBI and Holley TB unit, Holley projection intake,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip

2000 Kawasaki KX 125