IMHO... re-mapping and PowerBox has their own pros and cons... re-mapping will take a long period of time! PowerBox is plug & play and you will feel instant difference once you drive the car! My cousin installed one on his 523i and now his car is on par with my 525i in terms of acceleration and torque... I think some time not long ago in one of the threads here.. a forumer from Singapore (sorry forgot his name) mentioned that E60 523i with PowerBox will have the same output with 525i! I don't know how true is this coz my cousin didn't do dyno on his ride after that but one thing for sure is the instant power... even I can feel it :4: