the only critique i'd say of them is apparently they're an absolute bitch to work on, apparently they had problems with the recoil shaking everything apart and solved it by adding the strongest threadlock they could find to everything.
I know, right? Thing is, it'll be completely fine as it comes. I'm constantly amazed at these upgrade packages - not at the cost (it is what it is), but at the gullibility of people that seem to think that because they offer it then the RIF must "need" to be upgraded!
out of curiosity i had a look at what they were touting for an e&l krink
funny that they're reccommending a polymer piston head and a sorbo pad on a gun that needs neither given the stock piston head is a mushroom type with no aoe issues.
oh and a new cylinder head for a one-peice cylinder/head setup.......
edit: oh and cerakote for a brand who's whole deal is the shinyness of their finish.....
https://www.patrolbase.co.uk/airsoft-assault-rifles-all?*brand=117