i just ran this!!.... Holy crap!! 
what a difference. you instantly feel the results!... i poured 1/3 down the the gas tank.. 1/3 under the oil cap... and for the vaccum line.. i didnt have an extra person w/ me... so while the car was off i poured the sea foam in the hose when the car was off.. plugged the hose back up.... turned the car on it felt like it was gonna stall but it started up and a ISHH Load of grey smoke came out!!... i repeated this step another 2 times... gave it some high rpms for 2 minutes while in park... then i took it for a drive.. ( i also re-oiled my k&N filter before this.. so it helped the feeling alot!) all i can say is i was very impressed. i think im gonna run another bottle before this weekend.
and no you dont need to leave this stuff in your car for 8 hours. 30-45 mins is enough