I'm getting ready to redo the air compressor plumbing in my shop with RapidAir Maxline 1/2" kit. I have a Dewalt 30 gallon compressor and am currently using a harbor freight filter/regulator that has the 1/4" outlet. RapidAir recommends their 1/2" regulator for their 1/2" line. I connect from the air compressor to the regulator via the quick connect coupler on the compressor since my air compressor is on wheels I do occasionally move it for outside/house projects. I was thinking about upgrading from my current regulator to the 1/2" regulator but since the connection to the air compressor is via the quick connect coupler would it really make any difference?

1/2" air line will flow far more than a small compressor will produce. I'll assume yours is around 1.5 HP, something around 5-6 CFM. Even with a 1/4" quick connect acting as an orifice, your lines flow more than your compressor will put out (assuming reasonable run lengths, like under 200 ft.)

You will get less pressure drop across the regulator and lower velocity with the 1/2 inch line. Those are good things.

I've look at airline plumbing shop kits from 1/2 inch up to 1.0 inch. I have a old 10.0 HP 100 gallon Craftsman, I think, maybe it is a Harbor Freight 10 HP 100 gallon compressor that keeps the tank pressure from 75.0 Lbs. turn on up to 125.0 lbs. turn off on the compressor, I'm torn between the 3/4 and 1.0 sizes
I've thought about adjusting the sensor valve so it turns on at 100. Lbs. and turns off at 150.Lbs. like a lot of the older units I've seen in many commercial garage's years ago
What say you guys

What do you hope to accomplish by raising the pressure? There is no advantage to running higher pressure than your process requires. Higher pressure = lower CFM, so you actually loose capacity by doing this.

Some impacts don't work well with less than 90 psi. Mine is set to kick on at 95 psi and off at 135. I have 3/4" main lines with 1/2" drops.

How do you lose capacity by packing the container tighter with more pressure?
I'm pretty sure if it has 40 lbs. of pressure it has a lot less volume that would have with the same size container at 100Lbs. pressure, correct
liquids are a different story, a ten gallon container can hold ten gallons of liquids, no matter if it has no additional pressure in it compared to having one hundred pounds of pressure in it, correct

You GAIN tank capacity with higher pressure (of course), but your compressor PUMP delivers less cfm as pressure rises, that’s why units topically are rated at two different pressures.

my 1/2" impact works the best at 105psi.
it's an ARO brand, [supposedly] made in Bryan, Ohio.
the 3/8" crapsman sorta works the best at 110, 115psi.
i have my compressor set at, on 103, off 140. it's a two stage [i forget the brand, Rand maybe ?] pump going into an 80 gallon tank, 1" line [black pipe] going into a 28" diameter, 65" long tank mounted in the rafters, then 1" line from there to 1/2" drops where 3/8" inside diameter hoses are connected for use. the pump is run by a 7hp [5hp running from the tag info] motor member Crowbait gave me. i don't remember what diameter pulley is on the motor, but it spins the 13 1/2" diameter compressor pulley over without effort.
when i got the compressor, it came from a body shop, and the air inlets were full of bondo and paint dust, due to the shop not changing the filter.........
i got a rebuild kit from a place in Erie, Pennsylvania, and it included almost every internal piece for the pump except for the crank, pump body and head.
it's been working flawlessly now for about 15 years, and doesn't use oil. i drain it every time i use it to prevent water build up.
however, i don't use it but every few days, so it will last me the rest of my time here.
a couple years [maybe 4 now] ago, i bought a sears brand portable compressor on wheels [you know the kind i'm talking about] with the usual bent axle [how does that always happen ??] and crooked pulling handle, for $5.00 at an auction. there were no bids on it, [the minimum bid was $5.00] so i bought it after the sale for the minimum bid. i figured the motor would come in handy for something.
i got it home and plugged it in, turned on the switch, and it immediately went to 100 lbs and shut off. as there was an apparent leak, i looked and found it was boogered up drain threads on the tank bottom. i stuffed it in a corner, and will "some day" get around to fixing it up. [i need all the "projects" i can get. keeps me out of trouble. ]
now back to your regular broadcast story..............