The amp is what clips and not the sub. Also people who claim to be putting xxxx more watts through a sub usually have no idea what they are talking about.
If the sub says 300w RMS run it at 300w rms. If you want to run 500w rms which your amp cant even come close to doing, then buy a new amp and sub.
If the sub says 300w RMS run it at 300w rms. If you want to run 500w rms which your amp cant even come close to doing, then buy a new amp and sub.