i used seafoam running through the brake booster vac line and my car gets better milage now when i just cruise. butt dyno says it feels peppier and i did have a CEL on but that was because i had the brake booster disconnected.
can't say that i regret using it at all. now that i know how sweet it works i seafoamed both my parents car and my sister's car and my other car.
i just can't seem to get that billowing smoke that everyone gets.. lol oh well