Based on the collective experience of the board here, I would not agree that an "easy" 20HP are to be had on the aftermarket front. Several folks have actually gone backwards when adding exhaust mods for example.
To my recollection, changes were made to the intake, exhaust and ECU in the 987 models.
I do not believe these are simply "bolt ons" to the 986 but your parts dept would know for sure, as well as be able to give you prices for the parts if they are indeed, add ons.
Don't forget labor costs, they can be a killer.
