SHS make the best gears, JG make the best HT motor both IMO. Get a dampener piston head to quieten the gun a bit or just get a systema,G&P or whatever.
First things first listen to the guy above, then deal with the other stuff. - You'll know what I mean if you've seen my DMR.starfolder said:Well, Personally, I would get 18:1 ratio gears instead of the torque gears. The motor you are using will be plenty strong enough to handle those gears. Plus your trigger response will be much faster.
I don't see a reason to replace the selector plate, tappet plate, or ARL unless they are broken. The stock parts should hold up plenty well enough.
And, because the 18:1 gears are full teeth gears, I would pick up any of the SHS pistons, they are all very cheap and very strong.
I love my Modify Polycarb Piston head. It is very strong and provides Excellent air seal for me.
I'm also willing to bet you'll need an air nozzle. Personally, I love Prometheus nozzles, but they get a little pricy. As long as the air nozzle has an o-ring though, that's all you need from it.
And don't forget that it's not the parts you put in a gearbox that makes it special, it's how you install them that's important. Tuning mods such as shimming, tappet plate sanding, teflon where it needs to go, that will really turn your gearbox into a solid DMR gearbox