I'm in the middle of a shaker 500 "upgrade" abomination. Equipment installed (by me):

Kenwood kdc-mp438u HU
Infinity 6822cf 5x7 front & back
JBL cs60.4 driving the Infinity's
Kenwood's Sub pre-amps to stock amp driving stock 8" subs

I've got the HU outputting full frequency to the JBL and using thethe JBL's HPF to filter out low freq.
I've got the HU's LPF for the subs set to 120Hz

The JBL is in the trunk and the power is run on thepassenger's side. The pre-amps to the JBL, theamplified front speaker cables and the 12v signal are run on thedriver's side.

This setup sounds like ****. No drums per se, no bass guitar, no lows. The SQ from my cheap *** mp3 player has better clarity than this ****en rig.[:@]

I was hoping some tight eights could carry the remaining low end and was also wondering if putting a couple of eights in the rear would be as good putting them in the doors - as far as mid-bass separation & drums go.

I like hard rock like Iron Maiden, Metallica, Stained, Disturbed, etc. But I get in my moods and want a system that'll reproduce whatever I'm in the mood for.

Thanks so much and God bless.

edit #1:
Infinity 6822cf speaker impedance is 2.65 ohms.
JBL cs60.4 minimum speaker impedance is 2 ohms

 

the factory subs are an 8 ohm sub, while they are playing with the new amp they are receiving half the power that the amp is rated as and they probably do not have enough power. If you are not going to use the factory sub amps then I would not recommend keeping them. You would really be better off getting a small sub, yanking out the factory ones and putting in yours. Have you bypassed the factory amps for the mids and highs? You need to, they will play better off of deck power then they will the factory amps.

 

Here's a reallybad drawing of how it's wired up.

The HU's Low Pass Filter (LPF) to the stock sub amp is set to 120Hz
The JBL's High Pass Filter (HPF) to the door & deck Infinity's is set to ~100Hz

The Kenwood HU has an option of turning off it's internal amps if running a separate amp. They say it helps improve SQ. Those amps are turned off and the SQ is still ****.

When the bass hits the map lights dim.

When the bass hits the Infinity's just make some crappy thud.

No bass guitar (I really want to hear Steve Harris' bass guitar tones)

Cymbols sound like high pitch noise **** - no distinctive crashing, top hats, etc.

Crappy speakers? bought these because I've always thought Infinity was supposed to be pretty good (not really good or awesome or whatever, but at least pretty good).

Thanks in advance for all responses and God bless.

 

The Shaker 500 doesn't have factory amps for the doors & deck ("mids and highs"). The Shaker 500 HU powers the doors & deck and has an amp located by the driver's-side kick panel to power the door 8" subs.

So, the JBL's amplified front signals are ran back up to the harness and out to the doors and the rear amplified signals are wired straight to the deck speakers.

 

Infinity speakers are known for their very weak midbass. The first problem with the midbass was purchasing those speakers.

Your best bet would have been to get a single 6.5 inch comp set for the front and some cheap rear fill to Low pass around 700 hz.