To all of those reading this post. EDGE is a great company to deal with. Aaron is top notch IMO.
I've got two boxes (one duramax, one cummins). I was also Beta tester for the 600. (and yes, you can thank me for my extremely hard work to insure that your 600 box is perfect :-laf )
Both my boxes work flawlessly, and I am very pleased with the results. There might be several boxes out their that have more HP, but at what risk are you willing to take with extremely high pressures or EGTs?
I'm sure EDGE is in this business for a profit, and I'm sure that they understand that not having a box for the 555 is lost opportunities, but you fail to remember that these computer control trucks are extremely complicated. IT TAKES TIME to develop the software to make it work. The market for potential sales vs. Invested capital (R&D costs) showes a higher return on the 600's over the 555's. Pretty simple economics.
(as a side note, Lightman, do you EVER say anything positive on this forum? you always moan and groad about everything. I can't recall ever seeing something positive come out of you

Jwilliams is right, if you don't like it, move on, quit crying or better yet, if its so easy, design one yourself and make $$$ )