Arcturus 8mm Version 3 PE Complete Gearbox Challenge Kit w/ QD Spring Change & Perun Mosfet
(Model: T-Plug)

"Disclaimer: The default settings are for an AK-12. I put this in an AK-105 and it took some programming and minor modification of the selector switch divots.

Pros:
-Makes even low end motors feel snappy, giving a high end feel
-Consistent amp draw from batteries/low resistance
-Programmable to the users preference allowing for variation of playstyle
-Shot consistency is really good
-Well priced considering the price of the mosfet alone. Since it’s prebuilt and has decent Arcturus components.
-Aesthetically pleasing, although hidden for the most part

Cons: (Not really bad things but key takeaways)
-V2 Perun fire mode programming changes rounds per trigger pull, but the V3 has profiles. This took away my ability to only remove the two round burst from the AK-12. Fortunately, I play milsim games that only allow semi for rifles.
-It does not come with a motor cage
-When on safe, the trigger stop is gone/unnecessary, causing normal trigger pulls as if on semi. Since it’s an optical sensor it won’t fire but seems odd.
-Makes them motors HOT HOT HOT

Overall:
If you can afford to slap this bad boy in your AK, do it. It make take some tinkering with programming to get it where you want it but that is by no means a difficult task.
I put this in my CYMA AK-105 and it’s a beast. I will be buying another soon.