as long as you dont go up or down more than an inch from stock, you'll be fine. depending on how good you are at jumping, and how smooth are, you may choose to go more or less travel. if you're just getting started, upgrading to a 5" fork, like a marzocchi dirt jumper (heavy, cheap, simple, and kinda poorly dampned), or a z1 (alloy, lighter, better dampned, but more $$). im partial to 01-02 marzocchi forks (i own 3), and you can pick them up for cheap. other option is to go to a 3" fork, like a manitou sherman jumper/stance static, which are great for experienced jumpers and smoother riders who just want a bit of cushion.