After purchasing a new HU, is the OEM amplifier worth patching into, or is it better to bypass it alltogether?

I am planning on spending about $300 on my HU and upgrading my speakers in the existing space. I would also welcome any suggestions on HU's or speakers.


1998 Black LX Sport
# 140609
A-6 Sidemarker Lights
Front Speakers:
JL Audio XR570-CX