Some good changes, but quite honestly, for those with a D413 already, it may be worth waiting to see if upgrading just the differences isn't a valid alternative.
Chassis/Center Shafts/Arms/Towers (maybe?) being the most notable changes I think? Many D413 racers may have already purchased the Exotek split diff mount, so no added value there. Same with the aluminum caps. Will see. If looking to have an "Extra" buggy or wanting to give HB a try, by all means, seems like a cool kit.
I know there's a lot to be said for keeping some things the same (if ain't broke (or doesn't break!), why fix it?) I get that! For many, including myself, I'm just a racer looking to have some fun. The HB is a great car, and I've had a blast with it. I'm just looking for something different. Not because of any flaws with the HB...not at all... Just looking to switch it up. Sadly the changes in the D418 aren't enough to peak my interest. If I was driving something else already though?......I'd be all over it!! Looks like a solid kit!