I did a write up, in the Audio section, on how to upgrade the subs.
You'll need to source 10" LOW PROFILE subs.
I installed a pair of SKAR Audio 10" subs and a 400 watt Kicker Class D monoblock amp. 10x better. I actually have bass, now.
The OEM cabin amp will NOT push any aftermarket sub. Each channel is getting about 75 watts RMS. 95 watts peak.
The Hellcat dual sub is fed by three 75 watt channels, from the cabin amp, that are filtered to a mid-bass frequency, not even bass imaging (20hz).
Here's a link:
https://www.hellcatforum.org/threads/how-to-upgrade-the-dual-oem-hk-woofers.4596/
Take a look at the pix of the OEM speakers. They are a joke.
Hope this helps.