Andrew:

 

In my case I would have liked to try an under wing location (aka Spitfire) but not being an engineer of any type I didn't feel comfortable trying to plumb things through the wing spar, etc. so am opting to place everything under my Sam James "Rotary Cowling".   A Canadian Subie guy (Ross Farnham) is doing some interesting things with his RV-10 Subie installation in terms of placing his water radiator on the belly of the a/c; so you might want to check out his site and check back from time to time on his progress.  He is great about telling it like it is...good, bad, etc.   He already has a flying RV-6 and detailed all his cooling trials and frustrations and fixes that finally worked in that installation.

 

Doug Lomheim

RV-9A, 13B,

FWF