have been wanting to post on my experience having 2 x 525efi’s rebuilt by Merlin Marine in Buford Georgia 2015-2016 but did not want to jinx myself.....well just had the 100 hr service done last week at Merlin and no issues, total hours now about 600

bought the 2003 boat in 2015 with about 470 hrs on the original motors and went to Merlin for advice on next steps, they suggested minimum we do top ends but I wanted to do full rebuilds so he put me on the list behind 3 or 4 other builds he had going
The motors were bored .030” over but otherwise rebuilt to stock specs with better parts where needed. Typical issues were found during teardown which included a broken ring, leaking headers, damage on both cam shafts and a head gasket near failure, interesting since the motors started and ran great prior to tear down.

while the motors were out I decided to add extension boxes and new transom assemblies, which lead to shorties then to 5 blades and so on and so forth.......that is when the fun began
turned out to be a good decision as the existing assemblies had some damage that you don’t want on a 100+ mph boat

Tony handled getting the boat dialed in after so many changes which included having the computers sent out to up the rev limiters as the last change. Others have posted on this 525efi mod and have to agree a smart mod in this case that allows me to keep the same pitch props for easy on plane and overall performance
what I really appreciated was the cost estimate he gave me over the phone in October was the same on the final bill in May, does that happen anymore????

big thanks to Tony and Denise at Merlin Marine and highly recommend them to anyone looking for high performance expertise in the south east. Pat

Another rigging issue Merlin solved for me that was driving me crazy when I bought the boat.

Prior to the rebuilds and the extension boxes, etc......the port motor seemed to run 300-400 rpms lower which we thought was maybe low on power or the props were off a bit? After the rebuilds and new shorties and labbed 5 blades it was better but still at least 200 rpm off.
At the same time the stbd motor would run hot if extended running over 4000rpm. Merlin went thru all the cooling circuits and heat exchangers and water pumps without finding a root cause. He finally had to run the boat at speed with a scanner on it to find low water pressure on that side.
after a bunch of measurements decided the drive on one side was a hair higher than the other so added a spacer which solved the temp issue and the rpm difference, maybe that is typical with twin engine cats?

anyway much better balanced now

Love hearing a good result. :thumbup

F2- I think the term he used was gauled on the cams which I guess would be on a lobe?

Tony and Denise are great, they are the only ones I trust with my Apache. Always helpful and great people.