smoke domain size problems 2.57

I seem to be having this problem with my smoke where i scale the domain in object mode and the smoke sim scales too. Even when I rebake or even create a new smoke domain.

How can I increase the size of my domain object without influencing the smoke sim?

(working in 2.57)

any suggestions or help would be much appreciated

As far as I know you have to scale it to the size you want before you simulate the smoke.