Boost referenced timing retard

MiradaMegaCab said
MSD has a 6BTM box.
Same as a 6 series but with the tining retard Bill is describing.
I saw one for sale here, maybe MoparDude318 had it listed.

Summit has it for $379.97

http://www.summitracing.com/parts/msd-6462

I don't know exactly what the extra $120.00 buys you.