Ever since I built the Legend Gundam, I've been thinking about making a Seed-type unit, so I opened it up.
This kit is exclusive to Premium Bandai...it's such a good kit that I wonder if it will ever become a regular version!
The MS Advanced Joint only has two parts, so there's no need to worry about the arms or legs sagging!
This Impulse even has a combining transformation mechanism! RG is truly impressive.
So, here's a slideshow to help you imagine the transformation scenes!

RG Sword Impulse (spec. II) | ひこりん's Gunpla works