mazdaspeed protege system build

I was reading a manual for a precision power A600/4 amp that im interested in using to power 4 PPI 355cs component speakers and found a wiring diagram that stated "for a system over 300W run a ground cable directly to the battery instead of grounding to the rear chassis" I have never heard of this "rule" before and was wondering if anyone actually follows it? Also I have not purchased the amp yet and wonder if any one would recommend it to power those speakers because its S/N is -87dbA and RMS is 50w X 4 @4ohms and the speakers sensitivity is 86db with a recommended power of 50w to 100w RMS. I don't know how the S/N ratio affects the power output of the amplifier and if i should find a more powerful amp. Thank you anyone This is my first post but not the first time I've used this website/forum.

By the way this will be my second system that I have built but the first only cost me about 5-600 bucks so this will be my first real system and its going my 2003 Mazdaspeed Protege.

so the S/N is the signal strength from what compared to the background noise of what ? And this basically tells you how clean the signal is that your speakers are getting. Correct?Dodge Magnum in progress:

Pioneer DEH-80PRS - PPI Amps - Dayton Subwoofer(s) - Exodus Anarchy's - Vifa Tweeters - Kinetik Battery

update: I bought a Boston Acoustics 504 amp (50W X 4) and it was no where near powerful enough for my speakers I just looked up the power rating of my home surround receiver that I had them hooked up to and in stereo mode it gives them 110W RMS and sounds good so knowing this I'm now looking for an amp that pushes more than 50W. Some amps I'm looking at are the alpine PDX 5, PDX 4.100 plus a 1.600 for sub, or the new pioneer PRS D4200F and a PRS D1200M. all of these amps are the newer Class D ones that are coming out and from the reviews I've read including one from haemphyst on this site. any one know much about these AMPs avdice is welcome especially on the Pioneer one. Thanks

Another set of amps I found with the ICE power technology in them were eclipse amps they are a lot cheaper than the others but that's probably because 1 there going out of business and 2 there older (in technology years) again if anyone has these or knows about them tell me what you think.

Thanx that's exactly what I wanted to hear from one of you guys. I've been looking at these amps since early 09 but just didn't have a car worth putting them in yet now that I have my MazdaSpeed Protege I'll grab one maybe two of the XA4200's and and the same for the XA1200. I'll probably need some advice in the future about some mid-bass and sub woofers. Actually last night I read through Heamphyst's system build and the one he helped the SLP guy build in his tahoe and saw that he recomended several speakers I have also researched earlier for home theater stuff. I was wondering what sub you would pick between the Eclipse 12" SW6210 http://www......com/item_11724_Eclipse+SW6210.html and the Dayton RSS315HF-4 12" http://www.parts-express.com/pe/showdetl.cfm?Partnumber=295-464 there he same price the only differences I found were Xmax and Fs thanx again

OMFingG I'm 1/2...1/3... maybe just 1/4 of the way there but I have MUSIC!!! So I got my Eclipse XA4200 last week as well as my new 4AWG wiring kit. I spent ALL day Sat making 6X8 to 5-1/4 adapters out of MDF, running 14AWG speaker wire(darn door molex's PITA), modifying my stock tweeter pods, installing woofers in newly made adapters, running new 4AWG power wire/ground (had 8AWG), also ripping out some stock wiring for factory amp that doesn't exist, and putting all the interior panels back before dark. Whew... Today I mounted my XA4200 to my sub box and hooked it up. Front L/R are powering front L/R and rear L/R are powering my 12" Infinity (300W RMS). I installed the PPI 355cs crossovers under the front seats the beasts. I hot glued the inserts I made for the tweeters to the factory "module, piece, thing" and screwed the tweeter brackets to them, then installed them and the tweeters in the car. Then I re-connected my battery adjusted the crossovers so they wouldn't affect the HU's Auto time alignment/EQ and lowered the gains all the way. Next I turned my HU on and set the gains. While setting the gains to "A Billie" because of the repetitiveness of the song I was pretty happy with how things were sounding... Lunch... I let my Pioneer Premier DEH-P980BT do it's Auto TA/EQ thing and that's all folks. Results AMAZING: crystal clarity, tight clean bass, imaging, you can FEEL the mid-bass and mid-RANGE(snare drums), loud, doesn't make your ears tired at all even at high volume. The Wynton Marsalis Quartet - The Magic Hour-ALL tracks are great for testing imaging, bass, vocals, etc. Track #1(Feeling of Jazz) I love the upright bass (CLEAN) and the symbol on the left(CRYSTAL CLEAR) Diane Reeves sounds like her head is in my instrument cluster and when Wynton comes in scatting on his trumpet(I play trumpet)... the whole song sounds so LIVE not quite as good Imaging as at work with a pair of Definitive Technology Mythos STS Super Tower's (sound and vision's Audio product of the year 2009) but very good. Track #2 Good, but I haven't heard anything beat the Mythos imaging wise on this song the band starts the song by CLAPPING rhythms(lol you have to hear it, its really cool) in what sounds like a fairly small auditorium. Maybe later when I re-aim and make fiberglass tweeter pods and fiberglass woofer enclosures aiming them as well I will come closer to the Def-tech's (which for a reference R.A.PE an equally priced set of B&W's set up in the same room in mid-range, mid-bass, imaging, etc.) Some other songs: Embrace You by Chris Botti has been one of my favorite test tracks after listening to it on some Totem towers that had me mesmerized I think the silk dome PPI tweeters beat the Mythos aluminum domes on this song for a reason I can't really explain. Gordon Goodwin's XXL album- High Maintenance, Hunting Wabbits, and Horn of Puente (making my Bose 2.1 sound like doodie right now) Linkin Park - Cure for the itch Nine Inch Nails - The Hand That Feeds AWESOME LIVE sound Another GREAT very high quality recording is Santana - Shaman - Entire album OK I'll stop now already.

Pictures HU/dash before I'm scared by this... My wiring job HU/dash after Doors in Tweets in. I'm disappointed in the angle they ended up at but its temporary anyway until I learn/get into fiberglass then I'll re-do the whole doors. Sub/amp hooked up temporarily-ish as well. Damn that AMP works my sub gooood for only 200w box tuned to 30Hz. Not to mention my fronts.