While I do understand the whole "if the engine's not enclosed you can run automotive parts" argument, IMHO I always use marine parts on a boat. From what I understand the 6M-2 is basically an epoxy potted 6A. Now they have the 6M-2L, which has the built in rev limiter...basically it's a 6A-L that's been epoxy sealed.
The 6M-2 has a dedicated connector that plugs right into the MSD Soft Touch Rev Limiter so you can add a limiter to it. That is the current setup I run with the MSD R2R distributor and the Blaster 2 High Vibration coil.
With the box I highly recommend the R2R distributor over the pro billet. The pro billet requires the box to run whereas the R2R does not. It will run with the box...but the box is not required. Which means if you have a box go bad it's really easy to bypass the box and just run off of the distributor.
