Help me improve Rega P2

Wondering about the most (cost) effective tweaks to improve my P2. Currently have a Goldring Elektra cartridge and feeds into a Creek OBH-8 phono stage and then into solid state preamp and amp. Speakers are Symphonic Line Legato. I would think that a new cartridge might provide biggest change but wonder what others would think. Considering the Rega Bias 2 or Elys 2 mostly for ease of installation and alignment as well as presumed synergy. Certainly I'm open to other suggestions. Other considerations would be a new sub-platter(the one from Argentina) or new mat. Should mention that I have the glass platter, white belt and thick felt mat. Don't really have a specific complaint about the current system except that I suspect it can sound better. Perhaps more full sound or better bass. Willing to spend up to $300 so not interested in suggestions to get a better TT.
Thanks in advance. Jim