I have an early PSI screw blower that I would like to use on my boat. I sent it back to PSI and had them set it up for Gas.
What would be the best intercooler for my use? If I use an intercooler would I still need to use the plate between the manifold and blower? Any help appreciated. Thanks in advance.

No one out there has put a intercooler under a PSI?

Whipple makes a nice one, Richard Lee also, but I like the Whipple better.... you really need to put bypass valves on it as well so anytime it is in vacuum it recycles the air to avoid HUGE intake air temp increases which can cause rotor failure.

I used a Whipple intake and intercooler. It is very low profile. I did not want to raise the blower 4" with a standard intercooler. Also, the Whipple intake has a much larger opening than a typical roots type manifold. I had to make an adapter to move the blower 1" forward. Whipple mounts the blower in a different place than the typical roots manifold. The blower interferred with the distributor, that is why I had to move it forward. The adapter was only 1" thick and was o-ringed, so I didn't have to use gaskets. It worked great. Good luck.
Eddie