There is nothing in Edge's documentation that indicates any Ford product making 250 HP, flywheel or rear wheel. I'm not sure where the "250+ HP" number (located on the product overview page
Edge Products - Categories) comes from, but all the product specific documentation clearly shows significantly lower numbers. Just for reference, Edge's highest HP claim for the Evo is on the LMM Duramax, and that is only rated at 180+ HP.
Check here: Edge Evolution CTS and CS Reference -
http://www.edgeproducts.com/product_images/whats_happening_article-pdf-35.pdf
Also, all Edge products are rated at the
rear wheels, not the flywheel. The only way to accurately calculate flywheel HP is with an engine dyno. Since 99% of the dynos used are chassis dynos (of which Edge has 3), all comparison measurements and power ratings should be made at the rear wheels.
Finally, one of the main reasons many people run SCT is because nobody is aware of the fact that the Evolution can be custom tuned. It's not that the X3 hardware is any better or worse than the Evo, it's just that the X3 has historically been more flexible and there are a number of vendors that are able to write custom tunes for the X3. As more people catch on that the Evo, CS and CTS are also customizable, that may start changing a bit.
Take care.