ICS CXP APE questions/upgrade

[matas17]

So i just got ICS CXP APE from one of my friends for £265 with tbb and new hop unit/hop rubber. I was looking to upgrade following:
- Air nozzle
- Cylinder head
- piston
- gears
-mosfet

I'm looking to increase trigger response, since at the moment im using 7.4v lipo's with it and it feels sluggish for me. I dont know if i could correct aoe or short stroke piston and sector gear since it seems difficult on split gearbox. Also i dont know what kind of cylinder head and air nozzle it uses since iv never used anything other then m4. And i was wondering would i be able to install v2 mosfet into the lower gearbox without any trouble or do i have to do some modifications.