Hole saw- easier to get in the little area I have to work with. However I need to build a new upper ASAP

any updates?

Indeed-

Both upper drives were converted to XR Drives. I then ran the boat with the hatch cracked 3"- 72 MPH. I was like what the he!!, I'm going even slower. So I then pulled the flame arrestors and back to 79 mph +/-. So with the arrestor on, hatch closed 72 mph. So I don't think it was a lack of air issue, but a dirty flame arrestor issue. Even thought they look clean, they were not. I'm going to clean them and see how the boat runs this weekend, and I have a set of Gafrig 10'x5" air cleaners on order. So far now, those are the results.

did you try hatch closed arrestors off ?

dumb question right ?

Ha- not dumb at all. No, I didn't try with the arrestors off. I filled the boat up with gas, and running wide open drains the tank pretty fast. I need the tank full for this weekend, so my wide open runs were limited to 3 because I didn't feel like pulling the boat to fill it again.

You can cut a few layers of screen out of your stock ones. I only run 1 layer

I already sold the stock one's. Pulling them this weekend.

IF those were the ones that came with the engines they were already missing a few layers.

No- I put them on my old engines. I had HP 500 flame arrestors on it. Either way I'll be 100% fine with 10"x5" flame arrestors that are on their way.

I gutted mine and now just have 2 layers... playing with airflow things myself..