valve sizes

as far as speed control, you can use a 3/4" valve, but depending on how far your valve is from the bag & what size air line you run can play a big part in it too. A 3/8" dump right off of the bag could possibly be alot faster than a 3/4" dump that is at your tank & running say 3/8" line. I know that is a big streach of the imiganition & not very practical, but nevertheless another option.

So yes, if you do the 1/2" valve & the 3/8" valve in the identical location on the same bag, with the same size line, the 1/2" will be faster, but you will have alittle less control.

I have run 1/2 inch line and valves all the way around. My valves are mounted pretty much on the bag so its really fast up and down. After a while you get used to playin and can get your truck to lay out as slow as you'd like juss by flickin the switch quickly. Ifs its too fast you can always put reducers in the dumps.

get 1/2 valves and if they dump too fast for u then get some slow downs of speed controls