I don't know about a concave, I picked up a new buggy kit and this new chassis on tuesday and there was about 3 people at the store and some of them were thinking about ordering the chassis too so we pulled the one out of the kit and the new flex and laid them side by side and on top of each other and there was no difference. The only difference we could find was the flex one had a different finish(which I suppose is so when u see a darker chassis u know it's a flex) and the sides milled out. We weighed them on a postal scale and the flex was .8oz lighter.
EVerbody there was like I can do that to my own chassis, and there isn't alot of labor involved-I will do my next one with a air grinder with a titum tip and it would take like 5 min. I just like it how a popular buggy comes out with something new and say years of trial and they take a $50 chassis put it on a milling machine for 5 min and charge another $50, I would almost gauranty one of the losi drivers just took a dremel to a chassis and showed it to horizon and said this works, o well not the first $100 I spent on something so silly
