Red hot header pipe

Lean gunked up. Down here in FL, we can buy non-ethonal, still, in select places. Sometimes you can fill the old cars, without the 5 gallon cans hassle, depends on the owner. Downside- it costs more. Up-side= more milage. Buddy just bought a new $10000 outboard boat engine. I was there to ask ?'s too. He made sure that we understood. Costs more, better on everything, and makes more power. He said; run a full tank of eth in your lawnmower, time it running out of gas. Then run a tank of marine and see how much longer it lasts. Break-even, and saved working on it.