interested to find out if it's arrestors that held you back, or volume getting in / going thru the compartment

I'm going to clean the flame arrestor tomorrow morning, I'll post if I get close to the 79 mph mark with the HP 500 arrestors. I wish I had the Gafrigs so I could do a back to back test of the two

Don't the XR tops cause a smidge loss of speed as well?

So they say. But I don't have the props I originally ran to hit 80. Right now, I'm within 1 mph or so and that was with the hatch cover on and cracked vs 100% off. However, most will say running with no flame arrestor at all will also cause a bit of a loss in power.

updates? volume or arrestors?

Time for 8-71's with bird catchers sticking thru the hatch to ensure plenty of clean air!

I've got the new Gaffrig 10x5's and I'll be running them this weekend. I did run the HP 500's after I cleaned them and I only gained 2 MPH. I'm my opinion they are a big restriction. They really need to be gutted if you want to get the max power out of your engine. When I was cleaning them, I took the air compressor to blow out the carb cleaner, and it was crazy how little air pressure came though the wire mesh. I'd be willing to claim it was only 20% of the force compared to no arrestor. Either way, I'll soon report if a bigger arrestor in stock form makes any difference.

I bought the 10 X 5 for my 598. I do have ram air though.

sub'd

few years ago built a 489, with a 177 blower, Tom from weiand helped with setup, had a new eddie marine H/P flame arrester, 1st time out made 0 boost, was checking everything, found nothing. Called Tom, told me to remove arrester, popped right to 6psi ! so just because they look cool and say H/P does not mean crap ! Articfriends did a bunch of dyno test using EFI arresters and the results were very interesting.
I had some fairly large K&N ones I've had since 88 and now on my gibson, stuck one of those on and still had a tad over 5psi, many say they are junk but ???? so lots to be gained with just these...good luck keep us posted