iv tried a few different ignitions on my 7m over the 6 or 7 yrs ive had it no noticable improvement with an msd coil but a noticable improvement from the msd 6a multiple spark discharge but keep in mind it was camed up a bit and yrs ago i had the jacobs ignition and that def made a difference were not talking like ten horse or nothing but it was noticable un fortunatly it got fried and i settled for the msd