Am I crazy for doing this?
 

I am putting 2 memphis 12' subs and 6 1/2 diamonds with crossovers and tweets in the car with memphis amps, I wanna keep the factory head unit I don't wanna replace it.Is that gonna really affect my sound?

Yes. The factory HU on the base model is absolute garbaaage. I had it running a loc to an amp and it totally sucked while I waited for my replacement. I have an Osciloscope and can tell you the stock hu will clip at 2/3 volume.

Not true, if he does it right and uses something better than a LOC like the mtx re-q 5. This will clean his signal and flat line it before going to his new amps. I have done this many times with other systems and they sound great. OP do it right and get something better than the cheap LOC's from bestbuy. The JL clean sweep is good as well BUT one big draw back to that is that you have to mount a volume knob somewhere and use that. Which is stupid.

Of course notihg will beat the quality of a new head unit outputting a signal. But to me 2 12's in a z is stupid to begin with.

Why do you say its stupid to have two 12's? My amps are set up for 2 subs unless i can just not use one channel? i know nothing about this stuff.lol you really think one 12 will deliver the deep bass i need? i like loud deep bass

Ask trooper I had to turn his 600 watt amp down it was so loud with one 12 and yes you cam use two channels for one sub

If you crave bass and you have the amps and subs, DO IT.. I absolutely love bass that hits hard and clean in a sealed enclosure. I have a JL 12W6V2 in mine and it is being pushed by the JLHD 900/5 amp. It sounds awesome but I definitely could take even more hard hits with 2 12's.
You can always turn your gains down. Better to have it and not need it, than to need it and not have it.

Get a HU. They do so much more than just clean the line. I love my 5v preouts, customizable EQs, having 12db slope, using time delays, BBC optimization etc.

Also for a car this size, 600rms to a sub is plenty imo. If you want bass get one good sub instead of two weaker ones. You will save weight, room, money, etc.

For the record I have a Pioneer premier 880prs HU and a nine.1 pushing 600rms+ to my 13Ov2 subwoofer (12") in an RSX.

man I can't make my mind up! the weight of the boxes cant be very different, so it would just add the weight of the 2nd sub.and i kinda like the up fire box because it kinda hides the fact that theres subs in it..the box for the one 12inch is very visible..but i also understand maybe 1 is enough..ahhhh what to do what to do
:)

1...vented!

Plus 1 for the vented enclosure. A single 12 in a big ported box will deliver insane low bass! the output would easily exceed 2 12's in a sealed box in the 20 to 30 hz range. I built a system in RX-7 that used a 1.75 cu enclosure tuned to 20 hz using a JL 12W6 (original version) and pushing only 250 watts rms from a Phonex Gold ZX amp. It was louder, deeper, and sounded far better than the pair of 12" kicker comps I previously had in there.

If you go vented only do one because you are not going to have enough space for air to move back there.

^^^ +1 You're looking at close to 1.5 to 2 cu. ft. of airspace needed for a 12" in a reflex enclosure. With a little less than 7 cu ft of cargo capacity... ouch. Where ya gonna put the golf clubs? :D

So if I get a zenclosure box for 1-12inch sub can they port it for me?

every sub needs different spec for the port...you may be better off going custom.

The Zenclosures are little shy on volume for a single sealed 12" sub much less a ported sub. You generally need 30 to 40 percent more volume for a ported enclosure. If you are dead set on the Zenclosure box and want a vented alignment you may have to resort to a single 10" driver.

I have attached a software program that I wrote for calculating sealed and vented alignments and also it will calculate the optimum vented enclosure based on the speaker parameters used.

You will need to find the Thiele Small Parameters of the speaker your are interested in using, they are not hard to find.

You need the following values:

FS
VAS in Cubic Feet (You may have to convert from Liters)
QES
QTS

Also type in the value you wish to use for "Volume of Enclosure" By default I have entered 1

The values will be output to:

FCB
QTC
F3
FRMAX

all of these values will tell you very important information about how the driver will respond. The program will explain the values.

If you have any questions just pm me.