The ones for the supercharged have a timing retard that reads boost and retards timing. Plus you less likely to blow out the spark at high boost. Bob

 

I have an MSD with boost control that is currently not working , needs to be sent to MSD tech for repair , usually about $40 or $50 , these units are close to $400 new . I will sell the unit for $180 as is and you get it fixed or $240 repaired ($40 deposit required) . I have 2 MSD 6ALs I use now and don't need the supercharger unit.
PM me if interested.

 

I recommend you look at the Crane Hi6TRC. It has a boost retard and a rev limiter that's adjustable via a couple small dials instead of rpm "pills". More importantly, they seem to be more reliable than the MSD boxes.

 

I forgot to mention that next spring I will be taking the car for a dyno and have a chip burned for the computer. After the chip is burned would a MSD still be usefull

 

I have the same one as Wade. Has worked flawlessly for 3 years now.

 

I've got 6 yrs on my 6Al without any problems. I think any electronic gizmo can be have problems and both are likely good choices.Once when I thought there was a problem I disconnected it and drove for a while there was a noticible difference in throttle response even when not under boost. Under big boost there is no question that it's needed. If your planning on getting a chip for your car then a BTM isn't entirely needed but it's a nice safegard if you can't get good fuel.
I remember 20+ yrs ago when I asked my boss the same question about why we use to put MSD boxes in all our racecars his reply was. "do you want to start a fire with a match or a blow torch."
I've been a capacative discharge fan ever since.