Well, as a general/ rough guide for gearing things like the maxx, revo or flux with the MMM & 2200kv motor:
4s lipo = 40mph
5s lipo = 50mph
6s lipo = 60mph
Those are realistic top speeds for a truck in the 10lb region. As for actual speeds you should aim at, that kinda depends on the terrain and how much space you have. I use 5s lipo with the Medusa 36-80-2000kv motor, roughly equal in power to the MMM motor but a tiny bit slower; I gear for 40mph as thats plenty of speed for the space I have ( about a football field size area roughly ). 44/12 sounds fairly good for your setup, but you can always experiment a little bit up or down to see how you like the acceleration vs topspeed & see how the temps react; there isnt really a perfect setup or gear ratio, just whatevers right for you & what you're doing at the time.
Castle Neu 1520 on 6S LiPo Powered Gmaxx (Nitro Killer)
Predator with OS .21TM
Supermaxx with Mach .26
Revo with OS .18TZ
Kyosho ST-RR Conversion
Ofna CR with Tekin ESC/Motor (2)
Hmm, possibly, but it will be smaller in size so wont mesh very well, if at all, with the ring gear. Just replacing the ring and pinion gears shouldnt be too expensive, but it may require a bit of looking around- tower hobbies and amain should have the parts- check under hotbodies and ofna parts.
Rick, you can buy the 11T from the Hyper ST. They're straight cut gears.
Castle Neu 1520 on 6S LiPo Powered Gmaxx (Nitro Killer)
Predator with OS .21TM
Supermaxx with Mach .26
Revo with OS .18TZ
Kyosho ST-RR Conversion
Ofna CR with Tekin ESC/Motor (2)