I think I would change the throttle body entry from the top there to the front of the manifold.
Cheap way to find out how the air is being moved and how even it is being moved is to get a leaf blower and attatch it to your throttle body. Turn on the blower and open the throttle. It'll shop you how even the air flow ballance is. If your getting more air in the 3/4 cyl and less in the other you'll lean out in the middle and rich in the ends. If you have sequential injection you can tune each cyl. (Like you said.. EGT in each hole) will be able to "See" where your ballance problem is. Your Intake design is great.. just move that throttle body and it'll be awsome! You didn't post your actual MPH and ET for 1/8m.... ~Scott
