Go for it with street riding, that would make use of the bike you have. I keep thinking of swapping my stock frame and forks for more of a street setup.
Does it count if you are on a wall or on top of a building? If it does I can jump as high as you like. I was in an airplane the other day so technically I can jump around 30,000 feet
sounds a little like you are trying to hard. I used to get it on my DH bike when trying to do bigger jumps than I could. just relax and get really comfortable with the height you are at until it is so easy you almost don't have to try, then you can work higher.