it goes through out the intake, any where vacuum goes.
you pull the brake booster hose off the booster, then put your thumb over the hose, then start the engine, now pinch the end of the hose so the car will stay running, this hose being open is a huge vac leak, then pour the seafoam in the hose, it will suck it in. when yo near the end of your 1/3 of a can, dump enough in to stall the engine, then let it sit for 20 minutes, then fire it up and rev the engine, if its dirty inside it will smoke like a muther out the tail pipes.