FYI - the reason the XEDE piggyback unit cannot control or change the rev limiter is because these functions are hardset in the DME. There aren't any wires that you have to cut to get into the RPM system, it's "built-in". Nor can you undo any speed governors.
There's also another function called electronic throttle function (you can actually make it take off hard and pull instant, versus delayed). Sometimes manufacturers use this advantage to "make or kill power" (i.e. butt dyno). There are cars like Porsche (and BMW) that don't open at 100%... etc. There are other things here to take into account, but again, ALL DME functions.
At which point, you might be thinking, why not just do everything through a DME? Again, just FYI. Certain parameters just NEED to be done via DME.
P.S. This post was meant for informational purposes, not towards the pros and cons of a piggyback unit or DME functions.