cams and intake manifold make a huge difference. if you're running bigger of either of those your vaccume numbers will drop.

 

im running crane cams, thats prbably why then, thnx

 

i was wondering i got a vacumm manifold and im using about 4 of the ports . and also have the skunk2 manifold not sure what the difference is got it with the engine. well with all the extra vacumm ports does this lower my vac. and cause any problems?