I want to go with a better remote oil filter/cooler setup I kinda figured the stock one is not the greatest. I am on a small lake so it is never at high RPM for more than a min or two at best but still I want to do whatever will make the engine happier. What did you go with for a cooler?

It is 100% a MEF-1 ECU so it has to go, trust me I would love to save a few K but I think alot of my issues are this ECU.
As for the intake I would love to just upgrade the injectors, keep the stock intake and toss Holley at it.

MEFI 1 can even do what you want. It just can't deal with boost all that well. Injectors are a PITA for alternatives with that intake because they are Honda-Kehin style injectors - not impossible, just not an easy bosch/delco crossover. Get them from a good source and flow matched, lots of Chinese copy junk that will burn down your motor out there. You can have your stock ones cleaned and flowed, go with adjustable regulator, crank fuel psi up to 60 psi, and support your power goals still.

I went with a 3"x18" (Teague) cooler mounted above the bellhousing, -10 AN lines, Improved Racing thermostatic oil filter head, and new billet block adapter (rest from Summit).

Where are you located?

Putnam County within NY state. Boat lives on lake Mahopac.

When I pulled he rail the injectors have these black caps look like an adapter as the opening in the manifold is way to big for the injector so they added these adapters. To me this is juat another source of a fuel leak??

I will look into the parts you listed for the oil cooler, as for making -AN lines I have made way more in my time that I ever wanted too LOL I am a fan of Russell line and fittings.

A vacuum leak maybe, not a fuel leak from those black rubber grommets. Fuel is not in contact with them. I agree that it seems like a kludge of engineering but it's what we got.

Whoa whoa whoa.....don't just abandon the MEFI 1 just yet.... For the HP you are looking to get the MEFI 1 will work fine. The stock intake manifold with the previous version flame arrestor will likely get you the HP you are looking for. For your situation there are some serious advantages to sticking with the MEFI 1.

1) You have an ECM that works
2) Wiring harness works
3) Ignition system etc already tied in
4) MEFI 1, in spite of being the oldest version, is the easiest to tune (other than lacking fidelity in the fuel table)
5) You don't have to spend thousands on a new intake, ECM, wiring harness etc.

IF you are going with any boosted application, then yes, ditch MEFI 1, but that does not sound like the case.

As far as injectors verify the ones you have and their flow rate. They may be able to handle the HP you are targeting without blowing through the duty cycle. If you need higher flowing Keihin I have had luck with RC Injection in Torrance, CA. Not affiliated but they got me what I needed.

PM if you want to chat as I have done something similar to what you are doing with a MEFI 1 and would take pages to type out.

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Can you plug into a mefi1 with a laptop like Holley and make changes?
To me seemed like you needed an engineering degree to figure out mefi1 but I have no experience with it .

Yes, just need software like MEFIburn. I haven't tried it but the solutions are available.

I don't mind spending the extra cash on Holley if it makes life much easier, just need to do a few extra side jobs lol. I just dont want to be stuck fiddling around with an antiquated system fumbling around to find out I need to upgrade anyway. Plus if I ever did decide I want to toss the kitchen sink at it and feed it all the BOOST I know the EFI is already there.

Yes. It is easy but does have a steep learning curve. Is it as eloquent as the newer systems? No. The biggest problem I see is people start messing with things that don't need to be messed with within the MEFI 1 bin file. Fuel table and spark table are virtually the only two items you need to tinker with. There may be a few other cats and dogs parameters you may want to play with later but they are not game changers for initial tuning.

Use MEFI Burn to download the existing factory .bin file

Save this file in multiple copies.

Use TunerPro and open up a copy of your factory tune to dive into the fuel and spark tables.

Save this as a NEW file (don't overwrite the original).

Use MEFI Burn to upload the new tune to the MEFI 1. Takes about 3-5 seconds. Must be done with KOEO. No live updates while the motor is running. One of the downsides of MEFI 1 but not insurmountable.

The VAST majority of the scalars, constants, and flags shown in TunerPro for a MEFI 1 .bin file are actually not implemented nor used, so they do add some confusion for those looking at it for the first time.

Yes wideband is a must.

Heres some info:
A 525 uses the same EXACT injectors as a mefi1 454/502. I have found a 55lb import injector that I sell as match flowed sets, its slightly shorter so I machine bottom spacers to ensure it is in rail enough BUT your stock honda/keihan factory ev-1 connector injectors IF they flow fine will be just fine, I wouldn't change them unless when cleaned and flow tested they are terrible. I flow and clean alot of early 454/502 injectors and 525 injectors at my shop and for most part they clean up and flow fine.
Injector SIZE : your stock injectors are 48 lb, 48 x 8 is 384 lbs per hr at 3 bar (43.5 psi). 384 x 2 =768 , if your bsfc was .500 that means they would support 768 hp, assuming your bsfc is closer to .58 which is typical of mpi engines I tune and dyno you can deduct 16% from the 768 which would still get you to 645 hp maxed out. Even at 80% of that, it will get you over 500.
Stock fuel pump: stock fuel pump is 190 lph, its done at about 560 to 580 ft lbs tq/hp before injectors are.
Upgrade fuel pump/efi regulator /fuel cooler lines: IF your going to aim for more hp than stock fuel pump can supply and you upgrade it, you can got from 3 bar/43.5 psi to 4 bar/58 psi.
58 psi will increase the flow of your injectors by 15%, that 15% will take your max hp easily to 600 hp at 80% duty ccyle/.58 bsfc. I have pushed stock injectors close to 100% duty cycle over 675 hp with no issues.
Wideband/02 sensors somewhere in your current exhaust: If you do ANY mods, regardless of intake, etc, a wide band 02 sensor somewhere in your exhaust that you make tuning decisions from will keep you from running pig rich somewhere OR making pretty little piston ashtray gifts for your smoking friends!
Mpi Intake: I have made well over 600 hp/600 ft lbs of tq with mercruiser black intake by cutting down runners even with plenum floor/boring out TB and making 67 mm blades vs stock 60.
Flame arrestor: The flat plate gen 6 FA is a restrictive hp killer on modded engines
the Gen 5 mefi 1 factory fa is BEST flowing factory piece, those aluminum necked down adapters with clamp on KN fa's from various suppliers flow WORSE than stock and kill massive hp on modded engines
In recent testing I found the Gaffrig oval FA is by far the very best
Throttle linkage on edelbrock proflow (assuming you could actually get one), You put a throttle post thru side of their curved lever and make a bracket to bolt on side of intake, Ill post up a pic if I can find one.
Your boat in picture: Since its a single and doesnt appear to have sufficient room to put a large enough FA on the proflow, I wouldn't even consider it. A 90 KILLS a bunch of the hp gain that its known for. A proflow will embarrass a vic jr with a modded tb and good air flow but most that gain will evaporate if you clamp any 90 onto it. A merc mpi long runner intake will beat both a vic jr and proflow in early tq due to runner length at expense of top end hp but singles unless they are really a fast, stepped hull need square tq/hp. Guys get caught up on peak hp numbers that come from big cams, short runner intakes that sacrifice torque. Then boat sucks to drive, wont pull no prop. wont get on plane loaded down etc. If I think of anything else to ad I will, Smitty