here's my setup on my Sig 552:
-DeepFire titanium tooth piston (I put in good quality metal piston, piston head, and cylinder head with the sorbo pad in order to handle the speed and shock of the Lipo battery. Otherwise it will wear out very quiclky.)
-Modify aluminum piston head
-Modify aluminum cylinder head
-Sorbo Pad
-Prometheus M100 spring
-Modify air seal nozzle
-Shim kit (VERY IMPORTANT!!)
-Modify double-groove stainless bushings
-Mechbox lubed up good with Super Lube
-new Hop up rubber & bucking
-Madbull tightbore barrel
-11.1V Lipo battery (fits beautifully in the battery compartment; you will need a Lipo specific charger for the battery; Huang has them for a decent price.)
-custom made metal upper rail
(please excuse the colouring- came through kind of funny on the photo)
Also note- when putting the gun back together, don't overlook the need to properly adjust the motor depth. If the mechbox is properly shimmed, it will sound smooth, but you will need the motor gear to properly mesh for this. First make sure the gun fires and the motor is not grinding at all. Then slowly move in or our with the adjusting screw, and fire shots in semi. You are looking for the spot where you don't hear any gear turning sounds, only a SNAP. Or the closest thing to it.