Some people find that fittin a vent to atmosphere dump valve on the rev1/2 cars can cause bore wash/stumbling.

Its because the rev1/2 cars have an air flow meter, this measures the intaken air and flows the correct amount of fuel accordingly, the problem comes when you dump this METERED air

(air thats been recorded as intaken by the AFM) to atmosphere instead of re-circulating it back into the airbox like the oem bov does.

The engine will momentarily run super rich which can cause a stumbling idle

/ poor running even a stall out just after the dump.

The rev3 on cars dont have an air flow meter so they cope a bit better with this.

You cant re-circ the Blitz but ive heard you can recirc the HKS ssqv.

As REDmr2 says some people experience this problem and others dont so its a bit of a gamble really

The Blitz will fit all rev's of MR2 by the way

its only 1 bolt fitment on the intake manifold