Use the vacuum line right off your brake booster.
Make sure to have someone on the gas pedal to keep your RPMs up around 2-2.5k rpm
Dip the tube onto the bowl of sea foam and watch white smoke appear out tail pipe.
I would dip the tube, then pull it out, then put it back in a few times while doing it so the engine doesn’t stall.
Did it help? No idea really. Hard to determine performance increases....i know it didn’t hurt anything
i ran several cans of it through full tanks of gas. on a long road trip last summer in the hopes of clearing out carbon buildup that i assumed was contributing to pinging on hotter days and while climbing slight grades.
the only thing seafoam did was make my oil extremely thin. when i changed it - it poured out like water.
nothing worked to solve my pinging except running premium fuel and a good tune up.
I've never used it, but I know for 100% certain that just plain water carefully sucked into the intake when the engine is nice & hot will steam clean the intake manifold, the combustion chambers and the tops of the pistons so they're all sparkly clean.
Although I could never feel the difference, steam cleaning definitely cleaned stuff up.
I think if a water steam clean was done right before every oil change, the combustion chamber would stay squeaky clean.
I never bothered, but everything points to that being the case