According to an engineer at a reputable cage fabrication company (one that actually designs and tests cages in 3d before constructing), the stock evo X frame meets all of NASA's rollover strength requirements. So as long as you don't remove any sheet metal, you're plenty safe on a stock body X. That being said, a bolt in cage would and should only serve to add torsional rigidity for the sole purpose of improving handling. Anything more than that is excess weight in the form of redundant safety measures.

Modern vehicles are designed really well today. Nothing like cars from the 90's. An econobox made today is approximately 5 times safer in crash tests vs the best built cars from the 90's. As a previous forensic engineer, i've seen a lot of that crap cross my desk.

 

thats all true, and thats why the autopower rollbar is often referred to as just a glorified harness bar. but if your gonna run it the floor pan is absolutely too thin, so its a good idea to try and resist punch through a little more, since adding slightly more protection is never a bad thing.

 

I'm speaking specifically of the X, not the 8 or 9 in regards to roll safety. Though an autopower roll bar might still punch through the floor pan in a rollover, you're still exceeding NASA's rollover safety requirements on an X. If the car rolls over, the chassis is pretty much done. Who cares if it punches through?

Though on the flipside, If you use these bolt in cages as supports for a harness, then i'd agree you most definately want them to bolted to a supporting plate.