anyone have a guess as to why my car would now run with 15'' of mercury for vacuum at idle when i used to get 21'' ? if i told you i just replaced my intake man and TB you would have to suspect a leak , but wouldnt a leak that size cause the engine to race at idle - it would be getting air just the same as if it were let in by the throttle. vacuum lines are all ok. BTW i changed from stock '97 gsr to skunk2 and jg 65mm TB. any thoughts as to the now removed second set of runners in the stock man - this one is not only bigger , but just a straight shot to the ports. seems like maybe the increase in volume could cause a lower reading - plus the TB is bigger so the air could be a little lazy at low rpm. it moves up very quickly when the throttle is opened.