So I called up Koni today to find out the different between thgeir red "Specials" and the Yellow "Sports" and this is basically what the guy told me:
The only real difference between the Koni 80-2149 and it's yellow counterpart is the stiffness out of the box. He said you can gain the same amount of stiffness from the Reds simply by turning/stiffening the shock by about 3/4 of a turn.
My application is an almost completely stock IRS in a 71 Super, save for the urethane transmounts and CSP Kafer-Kup 3-bar Brace. I told him it was a streeter with a 2ltr T4 motor on 17x7 rims and that I wanted to lower and stiffen the suspension to give it a more sporty look and feel, but with the engine there is a bit more weight in back than a stock bug. He told me the Reds should work just fine, you can adjust the stiffness by turning the shock's body clockwise or counterclockwise to adjust the damper.
Clockwise= firmer
Counterclockwise= softer
He also told me that they haven't sold the yellow counterpart to the 80-2149 in years, but it was available and he could get it if I wanted. So if you do in fact want the Yellow Sports, just call Koni @ 859-586-4100 and work your way to the tech support part of the automated deal (I hate automated phone systems). tell them your application and they should help you.
Funny thing is, after all this research into coil-over conversions and such for my car, even after calling up Koni and asking them a ton of questions, I went with the Bilstein B46-0034's instead. Not really a matter of performance, just cost. I found the Bilsteins for about $60 cheaper than the Konis, but I was
this close to getting the Koni Reds:
