Well it's all fitted now and it's an improvement, not exactly belting out the air but it is better. The lower vents are great throwing out loads of air but the de-mist is still lacking.
There's obviously more to do on the ducting behind the dash, it looks like a really poor system for getting the air up top and the lower vents don't seal to well.
I widened the aperture in the bulk head so I know there's plenty of air in there, it's just a matter of ducting it properly.
Overall the air flow is better and there's plenty of heat, it's a lot quieter now too, even on full whack! This is good as that's the only setting at the moment...