I’ve copied my pm to you here for the benefit of all the other newbies lurking:
“Smaller machines pull chems better than larger machines. But that’s no reason to avoid going with the 8 if you’re able to.
I generally don’t advise newbies to go with an 8gpm machine unless they’ve really counted the cost. You’ll need a larger buffer tank, which means a heftier trailer and/or truck.
But if you plan well for it, an 8gpm machine can be a game changer.”
They do …
Sure, 5gpm pulls SH harder, but man does 8gpm reach a lot higher and rinse like a banshee.
I use a 65 gallon leg tank and yeah, it ran low a few times while rinsing but it’s nothing to just let it fill back to 1/2 and keep going.
As most can agree, once you go 8, you won’t debate!
I agree, @dcbrock…there is no question at all once you use the 8gpm machine…it’s just rock & roll! 
Today, I did this 4000sq ft under roof home and over 1200 sq ft pool deck (kool deck) in 3.5 hrs…drive up to drive off. Porches had spider webs, wasp nests, dirt dauer nests and walls and railings had mildew all over them. Yeah, I love that 8gpm machine.
Treefiddy for 3.5 hrs, not bad Jim! lol
Just a little more than that! 
Treefiddy is Florida prices Coop. 
Hey! That looks exactly like the house I washed in 2.5 hours and made $375…and no pool.
Ha, not north central fl.
I wash patio chairs around here for threefiddy, hahaa
Looks great
While there is a substantial difference between the GX390 and the GX630 in volume delivery despite the advertised 1 GPM, the wisdom of having a machine that requires 4 bolts to switch out engine or pump cannot be overstressed. When you have problems with the GX 630 or GX690, you’ve REALLY got problems. Just TRY to get those pulleys of the shaft of either part. What a freaking nightmare!
Oh don’t I know it. Just went through that whole mess.
The gear drives can be a pita also. Just make sure to clean the shaft well and use copper based anti seize and as a secondary measure put a light coat of high temp rtv to seal where the shaft meets the gear box.
Is it prudent to take the pump and gearbox off after a season and re-lube?
Nope…
Do you run gear drives?
I’ve got two that I kept when I closed the Florida location.
Sorry bout running you outta the state @Innocentbystander but once I saw how long your hair was…well you understand we gots standards in this state. lol
Full fledged mullet
Riiiiiiiiiiiiiiiight
