I have 4.30's in my s/c'd 99. A few things to consider though: 1. What tires will you be running? Street tires went up in smoke through 4th gear for me. Nitto's did good, but couldn't hold 1st gear with my old 4.10 gears. I now have BFG DR's and they keep the power planted in every gear...and that's with 4.30 gears. 2. Is it a centrifical or roots blower? You said KB, so you will have much more torque at a lower RPM than I have. In this case, 3.73's might be a better choice as I mentioned in my original post. 3. What transmission? I now have the Viper T56, so my first gear ratio in the trans is only a 2.66. That's a steeper gear by far compared to a T45 or T3650. So, my first gear matched with the 4.30's I have is like still having a 4.10 gear with my T45 ratio. But every gear after that is killer. When I'm WOT and shift to 2nd, the gear is over in about 2.5 seconds.... Side note: if you put that KB on, you are going to HATE that IRS...hop, hop, hop.....that's why I finally put in the solid axle.