I tried the MSD BTM box on my set-up (h20/methanol injection), but couldn't get it to work so I opted for the MSD retard box (I think it's 7982 or something) which drops the timing 4 deg (adjutable with plug) when triggered by a hobbs switch set at 6 psi boost. It's simple, cheap and has worked well for four seasons now, just not a gradual retarding system.
yeah, i keep hearing that about the btm's, but i'd rather remove too much timing than not enough.i'm new to blown jets and this set-up will be my learnin curve, plus the mill will get a dual plate system(nitrous) this winter and the btm will handle that for me