I have never had to straighten out a KDX, but I did repair a XR-100 rear sub-frame. The XR looked like it was about two inches off. I was able to fix it in about an hour. I removed the seat, rear fender, and exhaust pipe. I used a 2x4 (about $3.00 at the lumber yard) for a pry bar. I placed the end of the 2x4 near where swing arm pivots, this area is much stronger than the sub frame so the sub frame should bend before the swing arm pivot area will. I had a friend hold on to the bike, then I took an 8 foot long 2x4 and pried the sub frame back to where it was originally. Don't over do it. Pry a little on it at first to get the feel of it. The first few times I pried on it, the frame would just spring back to where it was. Then I kept prying on it a little harder each time and looked at it closely to see if I was moving the frame the way I wanted it to move. Keep prying a little harder each time until it looks right. The length the 2x4 gives a lot of leverage and no torch heat was required. I have about 25 years of metal bending experience so this was an easy fix for me. This repair method may not work in every situation, alot depends on how bad your frame is bent and your own level of metal bending talent.