Dont worry about blowing them. Just use the 24/db octive slope and set them around 70Hz and you will be fine. Focals are extreamly consertatively rated. Thier max rms rating is what I would consider a starting point.

Just wire the mid woofers and tweeters as normal and bridge the main 4 channels of the amp to the passive crossovers and set your crossover as stated above.

The dash is easiest place to mount the tweeters and they work very well there. I like what Big-A did with gutting the stock tweets and mounting the new tweeters inside the frame. No need to have them baffled since they are self contained. Set all gains at about 10:00 o-clock on the 900/5 to start with.

Thanks 2fast.

I just received everything including the enclosure from ZEnclosures which is nice as you said previously.
My other question for you is: should I have to use the rear left and right channels to hook up to the passive crossover?

Thanks!

only if you want to feed them 100 watts per channel. I would bridge the front and rear channels together. To do this look at your amplifier speaker outputs and it will show you what to connect. Its usually something like (Rt-Front +pos and Rt-Rear -neg and Lt-Front +pos and Lt-Rear - neg) This will yield you 50% more power to your fronts.

FYI its actually Front Left+ and Front Right-, Rear Left + Rear Right- for the bridging..
That HD900/5 is a sick amp..

Chill Liquid he was saying to check the manual to find out the correct way of doing it. Or the diagram on the amp.

?!?! was just an FYI.. no hostility meant..

Audio system installed today guys. It's beating up... the Focals are incredible and I'm happy with the 12W6v2 but the enclosure could be a little bit better in my opinion. I've noticed also that when I'm not listening music, there is a small background noise like "shhhhh" that I'm not sure whether is normal or not. I took the car to bestbuy but I don't know if that was the best option.

You have a little ground floor noise going on which is normal and to be expected. This is caused by a mismatch of gains or lack of balanced outputs between the headunit and the amplifier. (very few car audio head-units use balanced pre-outs - only the very high-end units) Since you cannot adjust the pre-out levels from your headunit the only way to reduce your floor noise is to use a pre-amplifier/line-driver to match the levels between these devices. You will never be able to get rid of all of it, only reduce it.

I also recommend stuffing your enclosure with about 2 to 3 pounds of poly-fill which will (I know it sounds strange) increase the volume of your enclosure by 10% to 15%. The polyfill will lower the FS (Lowest tuned frequency of the enclosure before -3db roll-off naturally occurs) Essentially the enclosure/driver work as if it were in a larger enclosure. This does come at a slight cost of efficiency though. With the amp you are using, you wont notice the loss.

I would re do your grounds, I have never heard that you can never get rid of noise in a system there is always a way without using noise suppressors. Start with your grounds and also check by unplugging the rca's from the amp and see if the noise is till there. If it is than its your amp ground if it is not it is your rca wires and where they are ran or further back in the system.

This is not an alternator whine or noise that is caused from a poor ground.

The noise he is refering to is the low level hiss you hear between the songs.

This is almost impossible to get rid off completely and largely becasue its already there in the recording from the recording equipment. Some recordings are better than others. On a CD look to see if its DDD, ADD, AAD type of recording on your cd.

AAD - analog recording, analog mixing, digital transfer;
ADD - analog recording, digital mixing, digital transfer, and;
DDD - digital recording, digital mixing, digital transfer.

A good DDD recording will generally have the least noise.

Your system will also generate some level of noise, everyones will to some degree. When you have your pre-out levels matched to the amplifier this greatly reduces the amount of hiss your system will produce. This is why having higher voltage pre-outs are very desirable. The higher your pre-out voltage, the lower the gains have to be set on the amplifier. The lower your gains are set on your amplifier, the lower the noise and more efficiently your amp will run.

^^ I agree

So, best thing to do is doing nothing...
Thanks guys

Sub enclosure in hatch in front of rear cross bar
 

[QUOTE=2fast4thelaw;503671]There are many photos and unique designs in my audio system on this site that speak for themselves. Everything in my car has been designed and engineered specifically for my car. I have even shared my subwoofer enclosure design with some of you that took countless hours of design and engineering.

Have you designed a sub enclosure in the 370Z hatch area located in front of the rear cross bar area (i.e. where the foam piece is located)? It may allow a 8" sub if the top of the sub enclosure is angled. I plan to install the amp (JL Audio HD 600/4 or 900/5 for its size) in this location as well. I plan on making the sub enclosure out of composite RFP (i.e.lightweight,dense,able to form curves). Any sub enclosure design thoughts would be appreciated! I can PM back with pics.