Thats how i did, Cut My x to 17", spacers Are cheap.

Sorry, not sure where I got the 26P from... sorry about that. Can you find a 23 Mirage (not a Plus) and see how that works? That's baseline for that boat with a 390 hp 502.

What shape is your 502 in? New? Rebuilt? Tired?

I tested a Non-Plus 23 mirage. 45mph @ 4100rpm. can trim it up to 5000rpm but no gain in mph.
Motor has been refreshed, new hone, new rings, valve job. had good compression. but maybe something is wrong with it? for me it feels like this 502 should spin a 23 mirage with no problems on this boat but what do i know

It should have no trouble spinning a 23p. My 242 with the stock 454 Mag would run 55 all day with a Mirage 23p. You should be seeing into the 60s.If you're trimming and gaining RPM but no speed, you're just slipping the and unloading the prop. 1.5-inch of change shouldn't make this big a difference.

Is the engine timed correctly? Setting base timing requires putting it into service mode and all that fun stuff.

Speeking of slip, do you have a drive shower installed ? I’ve run into a few boats (1 was mine) that had the pick up on the starboard side low enough that it caused slip.

I have a drive shower but its on the port side.
We only spin 4000 Rpm, so this is not that high number of slip. I start believing the engine is low on power. I will check timing and all.

Use this and let us know what you get for slip:
https://www.go-fast.com/Knowledge-ba...lip-calculator

with the mirage i have 22% slip
With the revolution 4 i have 10% slip