I can vouch for HBI. Have full compliment of their updates in my Scorpion and love them all. Each upgrade was well thought out and absolutely beneficial to end product.
Prostock extended charging handle
Duckbill mag release
AK style safety lever, right side only
- (safety off with thumb, safety on with trigger finger)
Trigger spring reduced weight kit
Theta forward trigger
Pakse Pathfinder grip