I would echo the comments of the other listers, and add that even the dual down can be improved with a little porting work. I matched the gasket to the outlets and removed a fair bit of iron from the inside. There were lumps of iron placed at the start of the runners to ensure there was enough beef in the casting near the outside ears if the inside cores shifted (as well as some other bits here and there). I made all the areas a smooth flowing as possible (removed the speed-bumps) and then had the entire set-up ceramic coated for about $75.

Should work great.
Craig