[hackerrei]

Well it said on the site for that stage you will need to have it but I ran the stage 2 for over a month and no problems but I am shure with a full cat back or even turbo back it would run better get more power and better 0-60 times then I logged 100% stock.
Mostly I look at it as a option because even with stage 2 the boost only hits 17 to 18 psi and the power gain is only 25-30+hp that is not going to hurt your car if you don't have the cat back but the map will not run as good as it would if you did and adding the turbo back or cat back will boost the HP gains over what cobb posted for the app its self.
But I will say that after using stage 1 for a few days at 100% stock it is better then running stage 2 at 100% the power feels the same and the0-60 times have a better avg.
0-60 stage 1 run 1 6.44 run 2 6.23 run 3 6.40 so at 100% stock this is a better avg then my runs with stage 2 100% stock.
So I will say after all the tests if 100% stock use stage 1 you can use stage 2 but the out come will be about the same.
If you have turbo back or cat back use stage 2 the power gains will be much better and the times will pick up.