I use " Dawn Power Desolver " and get it at walmart in the soap department, it's designed for BBQ cleaning. Just spray it on " it comes out as a jell " let it set a couple minutes and scrub with an old toothbrush ( you can use a new one if you want to ) then hose it off REALLY good brushing it a little as you hose it off . Works great !!! Just don't leave it on to long and be sure to rinse it well as if you don't it will give an etch look to your muffler etc..
ENJOY !!! RED