I've replaced almost all the internal parts.
Extreme-Fire SW-AB-Long MOSFET custom made without AB (yeah, weird I know ). I've replaced the fuse with one I made, and I've added a tracer unit control circuit of my own design, which enables any battery to be used with the internal tracer unit.
New wiring, using this 16 AWG stuff. It's nice and thin, but the insulation is tough and heat resistant.
XT-60 connectors - Loving them at the moment.
SHS High Speed motor - Excellent performance.
Modify 8mm ceramic bearings
Siegetek GS-R Revolution high speed gears. Siegetek gears are the best you can buy, and in my experience the only ones which can be considered reliable.
Guarder anti-reversal latch, but I'm currently trying to get the orginal one working properly.
SHS full metal tooth piston, lightened.
Trigger replaced with this micro switch, and installed this micro switch to activate the tracer. This took about two days of tuning to get right, but at some point I'd like to improve it with a more robust design.
Guarder SP120 spring - I haven't chrono'd it yet and I'll update when I do.
Air seal nozzle from AirsoftPro.cz
Sorbothane and urathane fitted to the stock cylinder head.
I'm going to experiment with a shorter inner barrel made by Madbull and appropriate cylinder that I have lying around, just to see how it affects the accuracy.
Guarder clear bucking, cut down to fit.
I have a few FlightTech LiPos that fit into the handguard, the largest is a FlightTech XS 2150 7.4V 50C (107.5A) measuring roughly 10.5cm x 1.7cm x 3.4cm
I always use a Wolfdragon PCB to protect my LiPos. I like the V4.x with trigger mod, which stops you firing the gun when the battery voltage drops below a safe level.
Think that's it, let me know if there's anything I missed!