if u are running a MSD 6a ignition u should get a MSD blaster coil...i have seen some that are made for the MSD ignition and also for stock ignition...i dont know what the difference is but i also think the MSD is 45K volts as apposed to 40K...i have also seen coils that give up to 70K volts...but that definitely would be too much for a street system...if u dont mind spending the extra few buck i would say get the MSD...but acell is just as good of a brand...but i think keeping the same brand of something the same...if u run full MSD ignition the i would recommed the MSD coil...although it really doesnt matter a whole lot i'm sure...just keeps brands together which is sometimes a good thing...