I don't think that you understand what happens to someone that modifies a car's ECU without telling their insurer, lots of people if unlucky enough to get involved with a car without insurance, ie get hit by it, might just want to take some serious action against the individual who knowing voided their car insurance - wake up!

CanI just ask when did I say I wasn't gonna tell my insurer please??
I ain't doing it yet you don't know the full story simply, I used to have a car for 6 months then someone crashed into me, so I've switched this car onto it, when I have 1 years no claims which will be in 5 months now my insurance will be lower and remapping the car won't put the insurance up too much