Help please! Fuel trim imbalance

Im looking for possible causes for my trims being off bank to bank by as much as 6% sometimes more. This makes it impossible to try and dial trims in close to zero. TVS2300 came with marine Delphi 42lb injectors issue was there, today I installed a set of deka 60lb, still there a little worse then the Delphi's. replaced o2's, no better, new gaskets under blower, no better, installed different heads PRC STAGE 1 317'S no better. plus plugs, wires, coils, no change.
Im looking for ideas on what to try. Im willing to go out a buy some Injector dynamics if this is just inconsistent injector function. thinking about just going OLSD and be done with trims. mods are 6.0,tvs2300,gt2-3, kooks LT'S, 1 bar maf but going SD but I was hoping to stay CL.

Exhaust leak? I would think that's the most common cause but it's the one thing you didn't mention.

Thank you I forgot to mention that I have replaced gaskets with new stock MLS a few times. Best I can tell no leak. But I will be checking again.

Always bank 2 is the leaner bank or the bank with the higher trim values

Is it worse at idle? I've found exhaust leaks to make trims be off much worse at idle and when you really get air being pushed through the exhaust it's not as noticeable.

Yes idle and light cruise. I was thinking about a cat issue? I was going to drop my y-pipe from the headers and see what happens. But that might screw o2 readings also if air gets sucked back up. Thank you for your advice. What is a good way to look for a leak if you don't here or see evidence of a leak ?

Rubber hose a few feet long and listen for air to blow out the end while running it across the exhaust. I've seen some people plug the tail pipe up to add back pressure also.

You're also right in your thinking that dumping the exhaust too close to the O2 sensors let fresh air mix with the air coming out the exhaust and make it read much leaner. At idle it's even worse.

Im going to try and unhook my bank 2 rear o2. I have them turned off in the tune. Cause I have my wideband. We're bank 1 rear o2 would be. Could this have a effect on the way the fronts work, because on is still plugged in and one is missing?