My 95 502 efi has separate coolers for oil/ps, the oil cooler is 3x18, I believe its the stock system that came with it. Your engine is making a 100 more horsepower than mine, ie more heat. I agree you need to move more water, and pressure regulated dumps is an easy fix there, but you're still asking the oil cooler to more than it was designed to do.
Kinda like asking 10000btu wall air conditioner to cool the whole house.

I'm just trying to make my system a little more efficient instead of spending thousands on coolers hoses etc. We are only talking about 15-20 degrees here. When i had the silent choice my pressures and temps were lower. Now since i removed the silent choice and added longer pipes oil temp and water pressure went up

I just called Eddie marine and they said a lot of guys dump some water before the risers. They have no problem with that.

here's the one from eddie marine that I run, works great..700hp
http://eddiemarine.com/engine-parts/...-1-1-4-slip-on

I have combos so if i switched to those I would also have to get power steering coolers also. The water lines on my coolers are on top and bottom not on the sides, I would have to re-do my 1 1/4 hose setup re-routing it out of the oil cooler down the back side of the engine then into the smaller PS cooler then another hose up to the t'stat housing and i would probably have to add a different type of oil filter housing with an oil thermostat like the HP500 engines.. I think i will just bleed some water out. Its starting to add up x 2

I have same ones from Mr. Cool...

If I wanted to spend as little as possible I'd:
-Thoroughly clean the existing coolers. Bore brush the tubes, solvent through the shell.

-Open up the water dumps on your tails and any other flow restrictions. Some time with a dremel should do this.

-Check the transom piece for corrosion.

-Inspect the suction hose. It's already off, give it a squeeze and make sure it doesn't collapse.

You might want to check the jetting on your carbs . after the riser change , u might have been running lean causing ur elevated oil temps.

Good point..............My end caps come off my coolers, maybe its time for a cleaning thanks

Update
 

I just wanted to say thanks to all for the help on my oil temp issue. After Running last weekend i decided to remove the end caps on my coolers. I was shocked at my findings. I can't believe the oil wasn't showing hotter and the engine water temp was at normal 152. SAND<PEBBLES>SEAWEED CLOGGED IN BOTH COOLERS.
Curious about the oil temps after cleaning

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Yea.... There might be your problem. Good find