I have built a few monster in a box transmissions, they are nothing more than a very complete overhaul kit with a fancy name.
Unless your engine makes more than 600ish hp, a good quality rebuild kit and a few cheap easy to do modifications is all that’s needed. Machine the direct clutch piston to accept a extra friction and steel (factory had 4 clutches, after machining you can fit 5). Install a wide bushing in the direct drum. Either install a shift kit, or internally “dual feed” the direct clutch. If your going to really beat on it, using a low/reverse one way roller clutch from a 4L60 is a good upgrade. The 4L60 roller clutch is a little bigger and a direct drop in swap. Careful assembly, new bushing and thrust washers, and your good to go for much less than 500.
If your making more than 600hp or have huge tires, the intermediate roller clutch is the biggest weak link. There are drum available in the aftermarket that have much bigger sprag assemblies. They are kinda expensive, but cheaper than fixing the damage when the clutch explodes.
And not to be a smart ass, my “technical assistance” on this forum is much better than what you will get from monster!!
