The air box mod and a new K&N filter has really made a difference to my bike. I thought it wouldn't help that much, but it really does add much pep. It also makes the bike sound louder and deeper. It is something worth spending your money on. Especially if you're going to put an aftermarket pipe on. Please leave a quick post if you have done this to your bike, and what you think about it. Also, post pictures if you have any.