I have a G-tech competition..
It has a built in tach with shift lights.
I do not believe that the HP ratings are coimpletely correct but, they do let you know when you get a HP inprovement.
Stock it showed my GT at 108 hp
With and Injen
catback and AEM
air it showed me at 125 hp
Add a 75HP Zex kit and it showed me at 210 hp