I seafoamed my 04 gt2 with 165K miles today.
I did not notice much of any smoke from engine, i put it straight into vacuum line. I used roughly 1/3-1/2 a bottle, let it sip about half of it, and quickly added the rest of it. let it sit for around 20-25 minutes then started but no smoke.
I did notice a little extra smoke from the exhaust right before i let it take the last of the seafoam, what did i do wrong