I have Kyle's coilover conversion, Upper a-arms, subframe connectors, 1 1/8 sway bar, larger centerlink, DSE tie-rod sleeves, AGR 12:1 box with 220 valving, DSE solid mount bushings, Hothkis rear leafs with Koni shocks on all four corners.
Though I only have about 250 miles with this setup, I can say it HANDLES! I dont have any true data, but there are a few curves near my house that all I could do was 65mph with stock subframe, Hotchkis front springs and 1 1/8 sway bar. With Kyle's coilover conversion, subframe connectors and a-arms, I recently went 75 mph with no problem. I think 80 would not be a problem. Car sticks with no roll or understeer. It felt just like a circle track car to me. You could feel the car actually rotate/pivot in the center of the corner, as if the car was picked up, rotated and sat back down.
For the money, compared to aftermarket subframes, It was a no-brainer to me. I would do it again. If you the fab skills to DIY, then thats more money saved for other goodies.
I've been to 3 or 4 car shows/cruise-in's and had many questions/comments on how the subframe looked, etc. Alot of people like the orginality of the stock subframe, but find it very cool to see its modified to handle with some of today's technology.
With all this, Is it the best handling frame compared to others? Cant say, need real data back to back against other frames, but I can say I'm very pleased with the result and I intend to try it out at Virginia Motorsports Park (road course) when I get the few kinks worked out.