As far as I know there is an optimum distance between a promoter and the gene for the best expression levels. What is that distance for common promoters like CMV, SV40? If you have a first hand experience about this (e.g. if you have cloned the gene way downstream of the promoter and didn't/did see expression) and share it I will be grateful.
If you have comprehensive knowledge for other promoters please feel free to add them in the list too; they don't need to be common. I just want to hear people's experience on the subject.