I had my MRT muffler for 3 months now and that nice shiny look is all gone. The inside of the muffler is all black and the outside is foggy with small back dots on it. Is that normal or am I getting some bad exhaust?

 

Well the inside is going to get black due to the carbon. All you have to do is just wipe the exhaust tips and you will get the shine back(if its stainless steel)

 

The black is carbon and there is no way around that. Just wipe it off like started above. Mine is a dirty goldish color right now. It will change color due to heat and dirt. Stainless doesn't mean it wont change color or get dirty...it just means that it will not rust. Im sure it can be polished back to a shine if you really like the look. I plan on leaving mine the way it is and just wiping it off when I wash the car. Performance, not looks. The MRT will perform no matter how it looks.