Ultimate+ Pedals on their maximum setting can handle incredible brake pedal force which allows you to get to the level of real life racing cars, however this can also cause some flex. This is an optional upgrade if you are looking for absolute rigidity with zero flex whatsoever at the maximum forces.
Solid steel plate with all the right slots and tapped holes
I ordered this Heusinkveld (HE) baseplate to make it easy to attach some HE pedals to my rig. The baseplate is perfectly machined to do the job. Attaching the pedals took a few minutes. Much easier and faster than trying to cobble something together from 8020 and a random plate to put my heels on. All the mounting hardware I could possibly need was included.
So far, it has performed as if it is a plate of steel. The finish is still unblemished after about 20 hours of having the heels of my shoes on there.