Homebrew Developer Akez has come out with the PSP Wave Change v1.2. If you've been using a previous version, it would be worth upgrading to this as it further refines the application and adds even more functionality to this robust program.

This software allows users to flash their own waves unto a PSP. Since it's initial 1.0 release, the developer has added a Graphical User Interface as well as removing the 20 wave cap that was in previous versions. In addition to this, the "up-an-down" bug has been fixed, making this a lot more reliable for prolonged use.

Note that the homebrew has only been tested on 3.52 m33-2 firmware, so it is still unsure if it will work on any other firmware. Akez has also given word that there is a slight chance that this might brick your PSP, so be sure to follow the instructions in the documentation of the program to minimize the risk.