I have an MX400Pro also and it flys great with
the Heli-Max 6 pole motor and an UltrFly 25A
ESC.

My son has the MX450 and it requires the AMMO
28 x 45 x 2700 which is a 500 watt motor. He
use's an Ace 45A Esc and that combo seems
about perfect. Motor gets only slightly warm. It'
has awesome punch-out power too.

I'd have to say the the MX400 size motor would
not work very well on the MX450... You'd burn it
up in no time in my opinion.

We both use 2200 mah 20c lipos...

I think 25c lipos would be a better choice tho.

AB