Nissan 350Z, Speakers and Amp Wiring?

I have a Nissan 350Z...I'm replacing the stock door speakers/tweeters and rear speakers.  I've decided on the Infinity 6010CS components *90W RMS* for the front

( http://www.circuitcity.com/ssm/Infinity-6-1-2-Component-System-6010CS-/sem/rpsm/oid/118645/catOid/-13092/rpem/ccd/productDetail.do)

and Infinity 6012i *60W RMS* for the rears.

( http://www.circuitcity.com/ssm/Infinity-6-1-2-Loudspeaker-6012I-/sem/rpsm/oid/119733/catOid/-13092/rpem/ccd/productDetail.do)  

I want to power the front components with an amp and possibly add a sub at a later time also powered by the amp.  Here's my questions...

1)  Can someone lead me in the right direction on choosing an amp with enough RMS power to use for the front speakers?  Would this work?...

http://.../prfap600.html

2)  If I plan on adding a sub at a later time, should I go with a 4 channel rather than a 2 channel amp?

3)  When connecting the speaker wire from the amp to the speakers, I understand it is possible to run the wire all the way to the speakers or just tap into the appropriate speaker wires in the harness.  It's obvious the second choice is easier, but which is best?  If I tap into the harness, am I using a T-connector or am I supposed to cut the wire in the harness?  Explain the appropriate way to connect the speaker wire from the amp to the speaker!!!???

Thank you!

Buy a four channel amp to power two pairs of speakers.  When you are able to upgrade, buy a subwoofer and a separate mono amp.  (Don't try to do too much wirh one amp...and since you're in the planning stage, you should plan to amplify all the speakers.)  It would work out best if you plan long-term when you are doing the power/ground wiring so that you will accomodate the complete system all at once.  Saves you from pulling out wires and fuses and redoing it all over.

Install sound damping such as Dynamat in the door locations and rear shelf for a much improved midbass response.  This damping will show to be a critical addition when you add the sub.

It's fine to run speaker wire to the existing OEM wiring if you want to avoid snaking wires into the doors.  Connect by cutting the OEM wire, solder the new wire to it and tape with electrical tape.  But, take into consideration that when you get down and dirty and into the job, you'll most likely find that it's easier just to run the new wiring directly to the new speakers.  The OEM wire that is left dangling must be taped up and secured so that no bare wire can touch anywhere.  This is standard procedure for all electrical changes or upgrades. 

Don't use T-taps.  You can't be assured that they will hold.  If you do use them, you will someday give this same advise based on your own experience.

Choose an amp based on the highest of the two RMS ratings...that is, the amp should not output more than the RMS but be enough power to satisfy your needs.  Going by this statement, if you bought an amp rated at 4 X 75 watts @ 4 ohms it is evident that the amp is fine for the fronts but too powerful for the rears.  That is not a problem, as you would normally play the rears at a much lower level than the fronts.  Either the fade control or the amp's gain setting can be manipulated to accomplish this.  But RMS rating isn't the holy grail of guidelines, either, because you can power a speaker very properly at quite a distance below the rating.  When you take a look at the amps available, you will see a preponderance of those outputting 50 watts/channel.  This is a good output for most systems and would work with both sets of speakers you mentioned.

I thought I read something that said the amp RMS rating should be equal to or more than the speaker RMS rating.  In your example, you said an amp rated at 4 X 75 watts @ 4 ohms would be fine for the front speakers, however, the fronts have an RMS rating of 90 watts @ 4 ohms.  Wouldn't an amp only putting out 75 watts per channel be too weak?  Also, I was thinking of only powering the front components with the amp and having the rear speakers powered with the aftermarket HU (Pioneer DEH-P6700MP), do you think this is a bad idea?  I figured if I did it this way, I'd only need a 2 channel amp, and I had been told the rear speakers in a 350Z aren't as significant as the fronts.  I was looking at the Profile amps, mainly because of price.  Would this amp be adequate since it puts out above 90 RMS @ 4 ohms?...

http://.../prfap600.html

If you think I should definitely run a 4 channel amp (or even a different 2 channel), could you show me which one you feel is best and explain why?

Thanks for taking the time to help!!!

The last line of my first post says:  "...50 watts/channel.  This is a good output for most systems and would work with both sets of speakers you mentioned."  I didn't make a typo here.

The speakers must be rated for a higher power handling capacity than they will receive.  You could use 200 watt RMS speakers with a 50 watt source.  The opposite is certain death for the speakers.  You hear and read a lot of things, for sure.  And nix the flea market amp brands like Profile...you'll be replacing it for an upgrade in no time and wasting money in the process.  Read through the threads here in this forum for a good idea of brands to look for.

You can power the rears off the deck but getting the sound right may be more difficult than you think.  You should be able to find 4 channel amps in your budget and then you'll be able to have the control over the sound that you should have.  And if I meant to convey any message at all in my response post it it this:  don't cut corners now because it will cost you in the long run.

PS:  pm's not necessary   )

Definately keep the OEM speaker wire.  Running the power you are looking to run (~50watts RMS) doesn't justify the pain and suffering it would cause you to swap the wiring on the Z.  You'll be pulling out harnesses, breaking waterproof connections, drilling holes through plastic, and praying you don't knick any wires in the process.  Check out www.My350Z.com for some DIY on Z audio.

Yes to the amp with less power than the rated rms. Think of it this way, your speedometer might read 240km/h, do you need to drive that fast all the time? What is more important that more power is clean power, clean power will make the speaker behave itself. Just remember that the music you listen to has peaks and valley's in it, your amplifier is not going to be governed, it will reproduce these peaks and valley's properly if you have the right setup. This is going to be all about matching the system together properly and then coupled with how you will use the system.

I personally would rewire the door speakers as I am a do it right the first time kind of person. You have no idea as to what may lie on the factory wiring between where you tap into it and where the speaker connects, what if there is an extra tweeter crossover for example, or what if there are only one pair of speaker wiress going from the car into the door? You would end up running new wiring anyways. Do it right, take the time and wire the new speakers properly. DO NOT put the components crossover into the door unless it is on the inside of the moisture barrier in the door.

I still need more info here. What is the headunit you are using, if it is the factory head (which I am assuming it will be), what have you chosen to integrate into it to allow a usable signal to get to the amplifier? As far as the amp goes, in you are planning on adding a sub, definitely look to the 5 channel amplifier. To me it seems that you are looking for a good tonally balanced system and not some annoy the neighbourhood bass machine. In this case a 5 channel amp fits the bill perfectly, allows for protection of all the speakers from the damaging effects of bass response at levels they were not designed to play at, allows for addition of the sub at a later date and finally should be far easier on space used, wiring bought and the potential for noise due to multiple amplifiers. One amp system in this case is the way to go. I also agree to lose the flea market brand amplifiers. There are a good number of 5 channel amplifiers on the market today, Crossfire VR705D, Eclipse PA5532 or EA3532 and others. Post up some info on the questions I have posed, if I am around today, I'll be glad to answer or of course one of the other members who are familiar with how I do things can also take over for me.