My experience with two MOPAR vehicles was that the stock system is a 2 ohm system. The stock amps, in a word, suck. I know it says Alpine...mine said Kicker. Neither company has a bad rep and makes some nice stuff. But I think the MOPAR engineer who specs the factory system is tone deaf. I ended up swapping everything out on my car and my truck.
I have an Audio Control LC6i 6 channel line output converter with summing. It gives me a high quality pre-amp signal for my Audison amp. The stock amp stays in place to provide that initial signal to the LC6i. Without it, I'd get a weak signal (or no signal at all) to the aftermarket amp. Comparing the system sound with and without the piece you can definitely hear the difference. The LC6i lets you add those aftermarket processors and amps while maintaining use of the factory volume and steering wheel controls.
I initially tried a set of Alpine speakers in the doors and rear deck along with some Infinity Kappa 3.5's in the dash with the stock amp. It improved but still sounded as if it lacked a great deal of power and quality.
So now I have:
- Hertz HSK-163 3 way component speakers in the front. The tweets are mounted in the upper portion of the door panels.
- Alpine SPS-609 6x9's in the rear deck for fill.
- Audison LRx 4.1K amplifier (the 4.1 means 4 + 1 mono)
- A Focal 33A 13" subwoofer
- Audio Control ACR-1 variable audio control knob mounted in the center console.
The only stock piece, besides the REC/NAV head unit, is the stock Kicker main amp which provides that signal to the Audison.
An 8" sub in the trunk won't be heard. I'd go at least 10" Type R with a 500W amp (MRP-M500) and a variable gain control knob.
JL makes some good stuff but ya gotta give them some power. Running them on the stock amp will be an improvement but you'll be looking for more soon. Infinity Kappa series are a nice, bright, tweeter but bouncing them off the windshield might sound a bit harsh to you. Any tweet there did to me so that's why mine are in the door panels.