Just installed the TWM short shifter. Easiest install yet. Took me less than 20 minutes. First of I like to say that if you have on 2007 SI, when it says pull the black piece up and back to remove, there is a little screw you need to take out first. I don't know if the 06 SI has the screw but the 07 does. After driving it feels so much better. I usually get the 2nd to 3rd gear grinds but now it feels so much shorter and barely could feel the notchyness. There is a little but not even noticeable. If you have 70 dollars to spend, I recommend getting the TWM short shifter. Combined with the skunk2 knob, it feels flawless.