Kicker has a great line-up here, look into there 6.75" subs, just Google. Great fitment in the stock console and gives you a lot of power for what you get. Pair of with a nice amp and you'll be happy.
Since you already purchased a 4 channel amp you would need to buy another amp, or return the 4 channel for a 5 channel amp.
+1 on Infinity and even Polks. Wish @Chris would update the sticky that recommends Polks to the new wave of speakers that are other there.
Some 5.25" actually play lower than 6'5", and I would go as far as saying that a bunch of 5.25" speakers will produce enough Wrangler TJ bass when paired with a subwoofer and a good front stage.
Send me the links to all the speakers and I’ll do that