Oh come on guys, if you fit a Viper it is generally accepted that the air/fuel ratio will be knocked out, this will therefore lose you power at some points and maybe even lean out a bit, BUT if you correct the fueling by means of a custom map or unichip, then you do indeed gain power over standard, you can look at a few example 172s that have had this done including mine Chris172s and Sluggers to see that - Shhesh! whats it getting like on here recently? all the info is out there....... and the is a search button you know LoL