Hi Senna!
In my opinion (just gessing) the new MTX5 will folow the steps of it's bigger brother, the MRX5. Features luke aluminium bulkheads, carbon reinforced uprights and maybe even a floating radio plate can be expected. Overal weight reduction compared to the MTX4 would be nice too.
But basicaly i hope that Mugen keeps it's "simple but fast" tradition!
And a car that is fully developed out of the box. Not like other brands that are still launching "extras" one week before the launching of a new car. You know what brands i'm talking about... That's what i never expect from Mugen. Probably what differs mugen seiki from the rest.