I am selling my SDT 4.0 it is just to much kite for me and I have only used it twice and just didn't like the power this thing makes. If you are looking for a good strong kite than this is the kite for you. I have all the original accessories that came with the kite.
More info
http://www.skydogkites.com/traction/sdt_4.0.shtml
Asking $300.00

My 2.8 is stout and fierce at the upper end of it's wind range(~6-25mph). I can only imagine the power of that 4 based on my experiences with my 2.8 and my 5m Flow.

The 2.8 is savage outside of it's upper limit. Been there before and kinda leery of experiencing that again...

I got the impression from the kite construction and handles it might be made at the HQ place?

I have a couple of each size, 2.8, 4.0, and 5.5. They are great kites and I fly them hard and often. They pull hard and handle well. The 4.0 is my go to kite in most cases. I mostly use to 2.8 as a demo kite. But if you look on the back of the cattaloge you'll see me flying the 2.8 is 30mph wind. I suggest you not try this at home. This is a good price and I only hope it sells for you quickly.
End of unintentional high jack

Yeah this is a nice kite but I had bought it to buggy with and I have never buggied. So I soon found out this kite is way to much to learn with, so I have to sell this kite before I can get a new one to learn with. But I do hate to part with it but I also want to learn to buggy so it has to go unfortunately.