How much benefit is realized just by getting the carb up and away from the heat of the engine?

Hatch Clearance

I have only twisted my 572's to 5700 so far in the boat, and they peaked at 6000 on the dyno with 9.95:1 compression. But I do agree tunnel rams are SWEEET and would love to have them! It would be very fun to do some back to back testing on your dyno :-) Originally we didn't plan on running both spacers but there was another one laying around so we tried it.

Almost same result here. Still a cheap 15-20hp!

Tunnel ram vs single plane 572 on smittys dyno? I like where this is going .

Jesel setup, why not throw in a cam swap while there too!

Maybe smitty could turn his dyno into the oso mythbuster. I would tune in for that show.

Just my .02, I did notice an overall difference (seat of pants) with the addition of the HVH Street Sweeper on my setup. Off idle stumble went away, smoother mid range power. Top end is crisp. I did back to back testing on the water one day between no spacer, mr. gasket $20 open spacer, and the HVH. The HVH performed well. I am running a Gen VI 454 .030 over, 088 Heads, +23 CC Domed Pistons, 9.6 CR, Stainless Marine full exhaust, Performer RPM, Holley DP, Comp Cams cam and valvetrain.

I wanted to do a test on the difference between SS and standard spacers.
Used 1" 4 hole spacers on my 540 builds super sucker on one, plain 4 hole on the other. On the dyno SS made about 6hp/12ft/lbs, in the boat shows up as 50-75rpm.
Not a huge difference but it's there.