Whether the mic is pointing up or down, it will no make any difference to the sound at all. The Mic can quite happily operate at any angle. To improve the sound you should look at fitting a pop filter to remove plosives:
http://www.dv247.com/invt/32655/ and also look into a reflection filter:
http://www.dv247.com/invt/31474/ or better still, give your room some acoustic treatment.
...and, didn't you ask this question before?