I got the self powered Rockville subwoofer. Fits perfectly behind the seat. Speakers are a dime a dozen, anything will work. I went with Rockville 8" component set due to the right size and low cost. I'm not using the tweeter.

Rockville RW10CA 10" 800 Watt Slim Low Profile Active Powered Car Subwoofer Sub https://www.amazon.com/dp/B019Z3R582/ref=cm_sw_r_apan_i_DDBV75E8JEN8FFQ4ABQS

Pair Rockville X8C Competition 8" Component Speakers/Titanium Tweeters Pro Audio https://www.amazon.com/dp/B07YPV4ZMB/ref=cm_sw_r_apan_i_956N6EDW4V6JKGYQBM8R?_encoding=UTF8&psc=1