I don't use the extra injectors(80lbs also),I run 60lbs in the rails,most boost I've ever seen is 4.5psi and I have(when I tried to lean the motor out for some type of cruise economy :D)seen a couple of degrees of retard here and there.when in boost,I run 31-32 ° and out out boost kinda aggressive w/ timing,all in by 3000rpms.I've been running it like that for 12yrs.run a full maximus 32pitch props,only thing That gets me on plane,so a pretty good load.I've never dynoed my motors.
how's your timing in comparison?

Awesome stuff. Love seeing these 454 build ups. Alot of guys toss their 454s aside as if they are a 4 cyl pinto engine. Truth is they can make some decent power with the right combination.

Id take a pair of of these over a pair of typical 650hp 540s anyday

34.5 total at 100 map at 6000 BUT using boost retard table to progressively pull timing out, pulls out 2.5 degrees at 150 kpa so really 32 total. Had alot of problems w motor breaking up on dyno under boost and pulling 7 degrees kr at 2500/3000 where timing was about 22 to 24, didnt do it na, looked at a mefi4b whipple tune file eddie young gave me for another sidemount i tuned on water on a 500 efi and it had similar timing tables. Swapped from stock coil to 55,000 or 60,000 volt dui coil and all break up went away w zero kr.

Smitty, did you do any adjustments with timing table in the lower rpms to see how affected torque?

i did from 3700 up, the motor actually made more tq down low than dyno sheet shows (sub 3500) but brake would not hold it, before water to brake got hot saw 600to 700 around 2800,3000, 3200 where sheet shows in 500 domething area BUT it couldnt hold the tq wo winging up to about 3500 , especially once it warmed up, the two sheets i posted i was at part throttle (2/3 or so) until about 3500 ish so i couldnt do.much tuning down there and will have to do it in boat, its a gopower 1000 but even when you look at 1500 hp brakes they are rated more like 800 to 1000 ft lbs tq down low,Smitty

322 Baja, only big prob i see is customer swears boat ran 68-70 gps w 1.5 drives, 23 merc 3 blades on bone stock 454.mags which is virtually impossible (prop slip and rev limiter dont add up) so when boat gains 16 or so mph from the 62 it prob ran and runs 78 or 80 he might be dissapointed! If these make 700 in marine trim as installed i dont picture it running much faster than 80, still a pig. He also bought a set of xrs w 1.36 gears and thinks hes going to spin 30s, again, i dont see it.

How do you make the MEFI recognize boost in an originally non-forced induction application?

Add a 2 bar map and scale the table? (at the cost of already course resolution)
Different VE table/spark table options with the tuning software that allow more columns for increased manifold pressure? (and obvious 2 bar map installation)
Other?

re-pinned his mefi1 harnesses to mefi3, rooted out the knock module, turned setting to "on" for 2 bar map sensor, added boost multiplier to bpw boost table (added 45% at 150 kpa, graduated up to that). I also switched from firing the injectors once every 4 stroke revolution to once every revolution, cuts pw in half automatically but then you add a little pw for the two dead bands. That helps even up the afrs in these mpi engines. I also developed the spark reduction table above 100 kpa. Because a mefi 3 is cruder than a 4 (boost table does NOT scale to rpms), you have to tweak the 100 map tables anywhere its rich or lean after finding a happy medium in boost multiplier table. I really like mefi now that i been doing it a while.
I invested in a 8 pak o2 sensor system too for my dyno so i can go back after pulls and look at sll the cylinders and quickly make fuel corrections, Smitty

Just as long as he keeps using the stock speedometer you're all good. I was in a boat that felt fast as he!! and speedo showed 78. My gps never went over 68 and that was fast enough. All relative.