Hello.....I have a 91 Gmc Sierra 4x4 w/ the 5.7L TBI (stock) set up.
Can I put the next generation vortec "swirl port?" heads on my motor, I've heard it will boost the compression in my motor too high. I want the fuel economy of the newer vortec without a complete rebuild. I was thinking of going with an EFI set up as well. Any thoughts ......................

 

Vortec was/is a loosely use term by GM where the results where better and in some cases worse.The train has pulled out on the use of O.E.M. Vortec head swaps mainly because beyond just the heads the total package did impact the rated output.Cams.etc.The good truck yrs are 1996-1997.Then the bottom fell out again for the yrs to follow.The reason why not to use the Vortec O.E.M. heads is it is true they raise C/R's,but the flow compared to aftermarket like well sorry for the lack of a good term,but they flow like crap.