Some of the details of the Impala chassis show the improvements on the chassis designs. This shock mount is set up to be the strongest possible without having to cut out the rear floor section as much. Plus it attaches to the front crossmember helping to square up the rear section of the frame and 3 different planes. 

In this picture you can see the corner gussets of the chassis have been thoughout and built to a level of being able to take advantage of every strength possible and do it in a sexy way. The vertical plates are all 3/16" thick and the horizontal plates are all 1/8" material to gain the beam strength needed of a chassis for a very big car. We are able to make our frame sit lower then the others because we do not need the same beam height due to the use of stronger materials. And with a shorter beam height you can make the chassis even lower to the ground with the same ground clearance or more.

When Detroit Speed brought their new 21.5" rack & pinion to market, Ironworks was able to improve on the design of their chassis even further. First we were able to use a rack that came from all new parts, nothing rebuilt or used. 2nd we were able to lower our rack position further to create more engine clearance. And we were able to shorten the steering arm length and not make the steering ratio too quick because they are the only manufacturers that we work with that makes a 21.5" rack and pinion with a 20:1 ratio.