Reading this might give you some insight how it can be faked..

http://www.land-and-sea.com/dyno-tec...-tech-talk.htm

Bump..and now this..

Dyno Problems & Tricks - Tech Review - Turbo Magazine

Seems to be a lot of arguments about who's is the bigger of late on many forums..

another tip when your doing your power run in 4th gear dont hit reverse, lol.

there is alot of talk on the web about people "rigging" their dynos to give unrealistic power outputs. the most common is "never trust your tuner, goto an independant"
there is also alot of variable, atmospheric temp/humidity/tyre pressures. people putting more pressure in their tyres to minimise rolling resistance just for a dyno run.