I have an ASM G3 just stock, but I was thinking about adding another Sedra 5000 as recirc so it'll have 2 sedra pumps on it, and then do the gate valve mod.
Didn't do anything yet because this would either be a backup skimmer or if I setup another system.
Well it comes with a Sedra 3500 stock so I would say the Sedra 5000 would be a good upgrade. From 350gph to 500gph sounds reasonable. The next pump from the 5000 is the 9000 and I think from 350gph to 900gph would be a bit much.