76 MPH on GPS and counting on a conservative tune. 8 mph gain so far. Still testing props.
https://youtu.be/r2QiV9bHmU4

Impressive!
 

That is impressive without a prop change! Nice job.

Thanks! Yeah, that's with box stock 25" Mirage Plus props that were already on it. It's spinning 5400-5500 with a heavy load and calm water so I have the owner trying the next size up and also some 4 blades to see what it does. I imagine it's going to see upper 70's when all said and done.

Eexcellent !

Got a little run time on my new combo. As stated , static compression dropped from 9:1 to 8:1. Replaced Dart heads which were around 319cc runner after CC'ing, with the EQ heads, that I had worked a little. The EQ runners measured about 330cc after CC'ing when done. I added intercoolers to the combo as well. Running 7.5lbs of boost with this combo, old combo was around 6.5-7lbs boost. Typical day with the old combo, 1/2 tank of fuel, some gear on board, boat would run 85-86mph. (best ever with light load perfect chop was 89.9 with old combo). Yesterday, full tanks of fuel, fully loaded cabin with all kinds of stuff she packed for the weekend, we ran 87.5 mph, with a little left.

So, to sum it up so far, I added around 140 lbs in cylinder head weight, 40 lbs worth of intercoolers, 60lbs worth of mufflers on the back, I'd say close to 250lbs of weight on the transom. I can definitely tell she sits a little lower in the water at the stern now. I added pickup for the intercoolers that add a little drag they say, and lost no speed. So far I'm happy with the head swap. I definitely think 8:1 with 7.5psi with intercoolers, is a safer setup than 9:1 with 7psi and no intercooler.

While I never measured intake air temps without the intercooler, this setup stays right around 105-110 when up and running. Today I was getting on plane, and making around 2lbs boost getting it up and laying over. I watched the IAT gauges creep up to 140-145ish , then as soon as it layed over, and water began moving thru the core, temps dropped right back down to 105*.

Good call and I would agree. Glad it worked out for you. I'm sure you had some concerns going into this but gotta be happy with the outcome. Just curious if you were able to leave jetting alone or did you fatten it up a bit?

All said and done tuning, boat ran 96.6 MPH, with 3/4 Tank of fuel, flat water. Back to back runs, so thats not a 1 time speed. Thats with about 1.5-2psi more boost than the old combo. Same props. Boat gained a solid 7+ mph with the engine mods from last winter. This year, she's put away and leaving things alone. Might get the props tweaked, but other than that, I don't think I can get much more out of these 468ci builds. Which kinda sucks, because the boat feels great at mid 90's. I havent talked to many , if any, who have taken a straight bottom 38 Fever to those speeds, and how the handling would be. She's a little light there, but very stable, and no hint of chine walk or anything weird.

Great numbers on a straight bottom 38 Fountain.
Any numbers?$?
As you stated earlier, they are a very nice heads out of the box and don't need much work.

I wanna say, with the porting, milling, valve jobs, springs, valves, flow tests, wash and assembly, i was in the 2500 a set range. I pretty much gave my head guy, free reign to do what he wanted with them.

I did help a couple friends out with specing out a nice spring/hardware/valve setup for these heads, and for two heads, with all parts, it came out to around 1800 a pair. Thats isky springs, ferrea super alloy ex valves, 6000 series intakes, etc.

Impressive numbers on all aspects, cost,hp, real life top speed changes, excellent write up, thanks for sharing.

Who is your head guy? If you wouldn't mind passing on/pm me his contact info that would be appreciated. After reading this i think this is the way I'm going to go.
Thanks again
Matt