Well I would try leaning out the low end thats what we ran into. When I got my new 3MM also seems that they are refining things does anyone have more than one I have 2 and the muffler down pipe went from being about an 1" to about 5/8" seems they shrunk it a bit maybe for back pressure. But the low end was about a turn rich so we leaned her down and she runs great now!!!