It's already been said but, I agree, wouldn't trying higher profile tyres seem better? I can't imagine any work on the suspension will be cheap. While the MG3 is certainly a little more sporty, I can't say I've had any problems with the comfort. It's not perfect, but it's perfectly enjoyable.
Of course, if you have the 16 inch wheels, I wouldn't drop too far down below this. Only to 15 if possible. I know some MG's have 14 inch wheels (which is what I'm familiar with) but I don't know about the size of the brakes on the larger model? Is it just the same or are the brakes bigger as well?