GV does allow gear splitting but you don't have to use it that way. I only use mine as an OD on the highway. It knocks off 400 rpm on the 50 mile highway cruise with 4.10 gear on my way to and from the track. The lower rpm reduction also keeps a larger duration cam in a usable rpm range to allow passing without kicking the OD out. I bought mine used with a good A999 for $1500.
I've run it at the track using 2nd over in the 1/8 mile and pick up 1/10. I normally run 1/4 mile and turn it off.
