If you really want to do something meaningfull, get a copy of Ricardo Wave (its on Isohunt if you look) and start learn about tuning the proper way, not by bodging a few bits of plastic out of an airbox. If you get good at it and understand the theory (it has some good tutorials) you could design your own cam profiles, exhaust systems, inlet manifolds etc etc using it although explaining how you got the package might be interesting.