Weight has nothing to do with how high or how big you go on jumps. That is determined by your pop and speed on take-off. If you weigh more, you will eventually go faster and you will go bigger off of jumps. The only thing losing weight can do for you is make your knees last a bit longer, and maybe you'll land a few more tricks. The best thing to do is work on your leg and core muscles, and work on flexibility, not lose weight, especially if you only weigh 167.