to those that drag race and expect to hit 122+ mph in the 1/4, i think this mod is a horrible idea. If you are going to trap those kind of speeds, you are more then likely going to shift to 5th and that extra shift will hurt your ET more then help IMO. Then when in 5th (i'm not a rocket scientist) but the ratio is less then 1:1 and i think your mph will stop increasing as much as say in 3rd or 4th gear and thus not helping the cause any more IMO.
This is just my take on this mod. I stress that it is my opinion and i am no rocket scientist :). I plan on trapping upwards of 125-130 so i will not be purchasing these :(.
Great for those on stock turbos IMO. Also great for those with upgraded turbos who autox or roadrace but dont drag race.