I was in the same boat as you originally. My car I road race all the time, I take to autocross events, but I wanted more power. I went with Vortech with a centrifugal supercharger, primarily because my 10 years of racing experience and my knowledge of how these superchargers discharge power, the centrifugal BY FAR for a road racing car is going to be suited for you much better than a twin screw blower.
Those who are suggesting twin screw blowers know that the torque you get from a twin screw is almost instantaneous. Putting a significant amount of torque down
instantly is NOT good for road racing, nor is it good for autocross. I know this from experience, I had a Kenne Bell twin screw on one of my previous cars, and even at 2,500 RPM the torque was too big to put the power to the ground.
Now some might say, don't you want torque? That's true, BUT not the way the twin screw delivers the torque. Getting out of a corner, the most important aspect of racing, putting the power down out of a corner, is very difficult to do with a boat ton of torque. Where the centrifugal benefits is that it's a linear power band, still with a high torque level, but it's not going to cause a spin like a twin screw would. I personally prefer the centrifugal on my car because of that, making it easier to drive on the streets, and much easier to drive very fast on a track.
Think about it, seriously, you'll see where I'm coming from. I feel very adamant about the centrifugal for road racing cars, it's just too much torque on the ground too quickly with a twin screw. Hope that helps! Let me know if you have any questions
