Aft side...
Hi.
It's cold here in Norway too, so I installed the Vans shutter for the same reason.
I was unable however, to innstall it in FRONT of the shutter, so I had to install it on the AFT side. The reason was the shuttercable, the engine mounts and the oilcooler-hoses.
The result was NOT good, since the air leaked out through all the small openings around the ribs of the cooler.
The result was low oiltemps last winter.
Then I sealed all the small openings around both the shutter and the cooler with high temp RTV, and the result was MUCH better!
Now I have acceptable temps during summer, spring and fall, but I still have to block off 1/3 of the front face of the cooler with alu-tape during winter.
During periods of really cold weather (temps down to -20* Celcius), I've to block off 2/3 of the cooler.
I highly recommend the shutter, but it schould definetely be placed according to Vans drawings: in front of the shutter, if you can.
I've a Superior IO-360 and I think it's slightly differnet than a Lyc in the oilcoooler area.
Or maybe it was my FF-setup who didn't allow room for the shuttercable to be on the fwd side of the cooler.