Yep pooring it in the pcv line is a good way to clean #1 & #4 cylinder in the lower plenum. If You want to do this, and I highly recammend doing so, but do it the right way. I've done this with a 5 gas exaughst analizer and it cleans things up dramaticly and brings back some ponies. through the pcv vacumm line dosen't do squat!!!! look at where those lines go to. you won't clean the upper plennum or any part of cylinder 2 & 3 or any part of the VICS butterflys. On any vehical the vacume line closest to the throtle body(but isn't connected to the TB) is the best line cause it will clean more (or all depending on the manifold). On our Proteges its the same line for the 1.6l 1.8l and 2.0l its the brake booster hose. It plugs in the middle of the manifold so it will spread the cleaner evenly through the cylinders. Have someone rev the car to 2000-35000 rpms the engine will want to die but keep reven to keep it alive. suck about 20 oz. into the manifold and kill the motor. (must get VICS to open to clean those runners so try to keep it below 3000 then after 50% of the fluid is gone keep VICS open above 3000-3500 rpm max) unless you put a carberator on your car you won't hydrolock the motor. the motor needs to sit for 10-15 minuets to alow the cleaner to soak into the carbon. Try to start the motor then and pump the gas pedal. if at any time white steam (its not smoke so chill) comes out its 1000% normal. rev the motor for about 3 min. and let it idle for 5 min. then take it out for a drive to clear out the sytem. Basicly what you've just done is steam clean the inside of the motor. Works freakin awsome. after it stops steaming (with the Engine off) reset the ECU by unpluging both + and - terminals and hold them together for 30 seconds. this drains all eletricity from the system and resets the ECU much faster then waiting 1 hr. or all night. I've used sea foam before and its ok but GM Top End Clean works the best. Its about 6-10 dollars at any chevy dealer. it works in Geos BMWs Mazdas F1 race cars or any 4stroke engine. Ignore the GM logo.