I have to share my opinion on this one, but I hope it doesn't p155 anyone off too much....
Although we may prefer otherwise, speed limits are there for a reason and that reason is the safety of ourselves, other road users and pedestrians, particularly the speed limits in residential areas. Now, I'm not sure anyone could say that they ALWAYS obey ALL speed limits, but to question why you'd stick to speed limits just because you have a fast car is nonsense. Regardless of the potential of your car, the speed limit is in place for a reason and applies to everyone. I appreciate the performance of my car and I do use it when it is safe and legal to do so, but I didn't buy it just to break speed limits and race everything in sight.
On a humourous note, I was washing the car a few months ago when a kid in a lowered Corsa stopped opposite my house and called out "so when are we gonna have a race mate?". Needles to say I declined his offer!