He is using a manufacturer's product - https://www.atlasautoequipment.com/products/lifts/two-post-lifts/2-post-lift-accessories/extension-kits/base-plate-extension-kit-for-bp10000x.
I unfortunately can't add on such an extension kit. Atlas only makes it for their 8000 and 10000 series base...
The overall height of bottom plate lifts are typically two feet shorter than top plate lifts. I don’t have the extra clearance for a true top plate lift in this spot of my garage, even if I removed the drywall ceiling and had it go up into the attic area.
It is brand new. I'm not so much concerned about the warranty, I guess. I would assume if there was an issue and Atlas wanted out of the warranty they could find some kind of reason?
To your second point though, I did read in another thread that adding a brace like that might negatively impact...
I'm installing an Atlas 9KBP in my garage right now. The ceiling is 10', so a bottom plate 2 post lift made the most sense. I've already stood up / positioned the posts and everything looks great. I'm wondering if I can add a steel plate (1/2" x 20" x 135", or 2 narrower plates for $$$ savings)...