Do it

Might as well start here and sell the current unit before it grenades'.

https://www.diamondperformanceparts..../products/1100

I stand corrected on the bravo 3 boat I mentioned, has ran 66, not 67, with bravo 3 and 71 with bravo 1, not 72

18k with no warranty 😕

Yep crazy I know but also proven to be reliable.

Would the lower really be necessary for boats sub 80 MPH?

Thats my thought as well.
I understand that even the B3 to B1 comparison is a moot point when dealing with speeds to 65mph.
Ive also read (and please correct me if im wrong) that the VP Duoprop drives are stronger than its Mercury Bravo3 equivalent.

And for the record... I am not here as a cheerleader for VP. I actually was shopping for a Merc 496ho package in this hull but they are rare as hens teeth.
I settled on the VP drivetrain because the rest of the boat warranted it and because it was still a Chevy big block.
It was only after getting the boat home in my driveway that I learned almost NOBODY has aftermarket support/upgrades available.
Sofar all I have found is Larry Hofer at Raylar offering the Gen7 BBC upgrade packages... and Hardin Marine sells Stainless Marine exhaust manifolds/risers for my VP combo... to which I am seriously considering. They are approx $3500 vs CMI stuff @ $8k+.
I still havent found a simple solution to the untouchable drive-by-wire Volvo Penta ECM.
Best option presented by Larry Hofer was to source a 420hp GXi ECM to swap with my 375hp Gi ECM. Still havent found one yet.

The performance increase that Im looking for is not unrealistic. The boat already runs an honest by GPS 55mph in bone stock trim.
I see no reason this thing cant hit 65mph with proper and realistic upgrades. Thats not asking alot honestly.

I have a new set of Gil manifolds with used dry pipes with mufflers in them that should fit that motor for $2500. I am only about 30 minutes from you if you want to look at them. for the record on the VP duo prop, I used to maintain an eliminator that had a 750hp Procharged 509 in it with a duo prop and it never had a drive issue in the 10 years he owned it. he was not abusive on it but did run it pretty hard at times so they are tougher than the merc b3 IMO.

The VP risers are pretty tall and have 6" spacers under them. I would definitely be interested in having a look at yours.

And yeah... im not abusive on stuff anyway. I drive very conservatively and safe... but do occasionally like to go hammer-down from a roll. I never vo to WOT from a dig. Always ease into it until im up out of the water and pull throttle back to maintain happy speed.
My full throttle blasts are typically initiated at 30mph+.
I expect this VP Duoprop to last me awhile.

And now that ive managed 10 posts i can toss a pic of the boat up. lol