Heat will be main issue, larger hose will help in that a bit but the constriction of 1/2" ports on the ram will be the main culprit. Speed- larger hose won't affect that again because of the ram ports. If the valve is all 1/2" also just money down drain with step up and step down adapters. Eons ago I rebuilt my splitter ( after bending mutiple areas including the 2" thick foot plate) my valve is 3/4" ports and hoses also but the ram ports are 1/2" my speed didn't change that i noticed but the unit runs much cooler. If my pump goes or the ram then I will jump to 16gpm ( 11 gpm now) and a ram with 3/4" ports. ( finding 3/4" ported ram is more dollars than the 1/2") Iirc the 16 gpm pump is still a 1/2 output port just at higher pressure.
