Mitsubishi did change their intake manifold design. If you look at Astron I intakes, the runners were pretty short and unevenly matched compared to the Astron II. There isn't a lot of room to add a complex and long intake runner on a 4G5X engine, but EFI on the 4G64 changed the layout enough to have a 2 piece intake with long curved runners. If you can't alter the intake runners due to space limitations, use a longer intake pipe (something I've been recommending to do for ages) I still want to get the lower half of a 4G64 intake, lop off the remaining runner tubes and weld up some alloy pipes for bike carbs.

Salteen - what is that dual down draft set up from?