Can't get more than 11-12 lbs out of my MC xpress

[hot rod rooster]

what i meant by vacume system was the place you have all your BOV's and regulators plumbed into. i guess it is sometimes a vacume and sometimes a boost system!LOL i have them all plumbed into the 4 nipples behind the carbs. i would shorten up the wastegate rod a bit and see if that helps also. you should have no trouble making 12 lbs boost with almost any turbo.(not on a 4 stroke anyways)