I'm going to hold off on the Gear Vendors option then. Hell for that price I would expect the gear splitting to work correctly.
It works but don't expect any of the dribble they advertise. When you look at the system you can see why, for starters, the OD on is engaged via a solenoid so pressure must be built up which in term takes time, around 1-2 seconds. Easy enough to get use to, just time it so you shift 2-3,000rpm before your normal shift point. It's good but IMO, only as an OD unit. You have to ask yourself, why not get a full proof A518, no "splitting" just a 4th gear, same as the GV except you pay half the cost (or less).
The good point about GVs is you maintain your #'s transmission. If my car wasn't a numbers car I'd pull the GV out in a heart beat and get a A518 or 5-Speed manual set up. To sum it up, I guess I fell for the GV blurbs on performance shifting, I was expecting pro-stock type 6 short ratio shifts but, ah, nope. Once the auto sequencer is finally worked out, which I believe mine is now (just giving it time to see if OD still wants to kick out, thus far, all good) I think it will be an "OK" unit. Just unfortunate that I was the guinea pig for Gear Vendors lack of product planning. I'd love to sit hear and talk it up as I own one but I can't, it's just not a good unit.