I do believe anything will be better than stock. Stock is practically silent until you're really on it. Sound is just too subjective and there are just too many choices.
What made you choose the Ark Grip over the HKS? I was comparing the two for a while as well, but eventually favored the HKS in the end. I like the deeper tone of the Ark, but the HKS higher pitch of the HKS sounds nice as well when it opens up.
The Berk sounds nice too, but for me, the HKS, ARK and FI are more pleasing to me aesthetically. I may have settled on the HKS in my mind. I probably am just afraid of regretting my decision. Information on the HKS Hi-Power is just so limited online.