Put a GAUGE ON IT AND SEE HOW MUCH YOU ARE MAKING PRESENTLY. ANYTHING BETTER THAN ABOUT 14" IS USUALLY GOOD ENOUGH UNLESS YOU ARE IN STOP AND GO TRAFFIC WHERE YOU COULD DEPLETE THE VACUUM QUICKLY. WE USE A FAIRLY STOUT CAM IN OUR 383 AND STILL GET5 BY ONLY USING AN AUXILIARY RESERVOIR. THEY ARE INEXPENSIVE AND IF IT ISN'T ENOUGH, THEN GO TO A DIVORCED PUMP SETUP. ONLY REASON I HAVEN'T USED ONE OF THOSE IS WE DON'T NEED THE EXTRA WEIGHT IN THE CAR. i DO KNOW PEOPLE WHO USE THEM IN STUFF SO RADICAL THEY SOUND LIKE A FUEL; CAR WHEN THEY IDLE. YOU WILL KNOW IF ONE IS NECESSARY IN YOUR SETUP BY BRAKING AND THEN BRAKING AGAIN SEVERAL TIMES QUICKLY IN SUCCESSION SO AS TO DEPLETE THE BOOSTER. YOU SHOULD NOT END UP WITH A HARD PEDAL WHILE DOING THAT. btw: WE CURRENTLY ARE RUNNING A VOODOO CAM WIT6H 540/560 LIFT. IT'S IMPORTANT TO GET YOUR TIMING CURVE RIGHT AS WELL AS THAT CONTRIBUTES A LOT TO VACUUM.
