I have a 1" spacer from
http://jomarperformance.com/catalog/index.php?cPath=38_39 that is an oval on one side and two holes on the other. You are supposed to run it on a dual plane with the oval side on the shallow side of the dual plane.
The theory is it will fool the manifold into believing it has equal plemum size on both planes. They claim a noticable gain in HP over a standard 4 hole or open spacer.
I'll send it to you to try on the dyno for a few weeks if you want. After the strange results so far it may be interesting.
