I've read a lot of different info concerning this. The range I've seen is that for each additional pound of muscle mass, the body burns 6-50 additional calories at rest. This is obviously a pretty large range and I tend to believe the truer number is more like 6 calories per pound and I'm sure it varies drastically by individual, probably more to the lower end of the scale.
This is why you go to the gym and see so many meat heads with tons of muscle and significant amounts of fat. The muscle isn't doing that much to burn additional fat, nutrition and cardio will be the elements necessary to burn more fat. Muscle mass will just give you a shape when you lose all the fat so you won't be a twig after the body fat comes off. My two cents...