I run 100% meth.
Why? because i am trunk mounted and stupidly used the 1/8 line ... so my pump fights a narrow delivery line with tons of resistance over length so mixing would reduce the amount of meth delivered in addition to the limited amount i get now.
if i were under he hood mounted i'd probably go 1/2 boost juice and 1/2 pure meth ..
eventually i will go with 1/4 braided line, nozzles etc for a trunk mount system.. but if i spend that money now my wife will MURDER ME ...