All hammer set upgrades are compatible with this kit, as it replicates a stock AAP frame.
As the kit takes a stock AAP Upper receiver, any bolt or hop upgrades are also compatible, however it is important to bare in mind any increases to cyclic rate will need to be carefully tuned to ensure the gun still feeds (this is no different to when running off a HPA adapter).
As always, incremental upgrades, by an experienced tech, are heavily recommended.