The new BTH mags are fine, I would not say they are bullet proof just like any of these systems is not either........With normal Mk 2 cams you should be fine.........My cams have far more duration than Mk 2's and this is probably why it was spitting back at idle speeds...........This was with a new Grosset ignition system with the dual output coils as they run these as well.........As you might know the new BTH mags run separate coils externally mounted under the mag cowl.........The BTH is a CDI ignition, not a coil ignition as the other 2 are.