I'm going with the 340 manifolds, although they are really expensive, I've got one half and got a lead on the other half for a decent price. See my other post in another topic about this. This guy here ->
http://www.ultrajosh.com/resources/ has done the 340 thing, click on exhaust in his left menu. Or go here ->
http://www.ultrajosh.com/myshop.htm to see photos.
340 HP Manifolds