I will tell you polk is the best I used to own a 2004 350z with polk audio mids, highs, and subs. I invested over $6k. It had DVD screen, Custom plexi glass box, capacitors, kicker amps, and coustom install. I spared no expense. However My Ram sounds just as good with a fraction of the cost.
This is what I installed in my 07 Hemi and didnt break the bank. My deck is a Jensen VM9512--7in dvd screen. I replace all the factory speakers with Jensen 6X9's and Jensen 6.5's in the back. I added DB drive 1" tweeters to my doors. I have a speed series 4 channel x 125 watt amp at 4 ohms for my mids and highs. The I have a speed series 1000 watt mono amp for my 2 DB drive 600 watt subs at 2 ohms under my back seat.
I bought the Jensen deck 4 years ago for $400 delivered via ebay.
Jensen 6x9's $50 the pair
Jensen 6.5 coaxial $29 the pair
The 500 db drive 4 ch was $179
I bought the 2 10" DB dive subs, Box, and DB drive 1000 mono for $399
The DB drive tweeters were $40 bucks.
I bought the amp kit on line for $60 on ebay. The Radio kit for $20 on ebay. Then i bought a 2 farad capacitor.
My sound system sounds killer and i saved about 4k compared to my nissan.