Another thing that can be done but has not been mentioned yet is changing your gears. This does not give you more HP, but it does help you get off the line quicker. However, you will see your top end reduced. So it all depends on what you really want to do.
From what I have seen, most drivers like to drive fast (read:quick acceleration) between 0-80 or so. They think that if you can make it to the next stoplight faster than another guy you have the faster car... this may or may not be true however.
But if that feel and response is what you are looking for as well (and it looks as if you are), you may consider changing your gears.