Got supership installed on my 172... It do make a power increase, the torque more responsive..... however, how much power it really increase, dun really have a clue.
But if you are living UK, u could probably try some other ECU upgrades, such as unichip etc.... People said they are better than superchip. Coz for superchip, it is quite restrictive, one upgrade, then thats it, no more change. There are some topics about ECU upgrade, just search for those topics.
Cheers