i really dont want to get into replacing head units, speakers, and custom fabricating elaborate or even semi elaborate boxes. all i want is about a 10" sub with an amp capable enough to run all the speakers plus the sub with very very little installation.
can this be done to our z's? i havent seen one yet that has been simple, every one has pretty expensive and somewhat extravegant setups.

 

do you have the bose?

if yes, then just replace the factory sub and put amp under seat

if not try an Infinity Basslink..it sounds great and has built in amplifier. I think someone has put it in the factory sub location..not sure how it turned out but do a search

 

this is what i did intially. i replaced the stock sub with a better 10" but had to tap into the sub wires and amp lead and ran them to a line output converter (cause the stock sub uses a weird fastener). i simply ran the wires from the stock sub enclosure and directly under the two small glove boxes and into the larger glove blox (behind the passenger seat). this is where i placed my amp and loc, and then ran the speaker wires back to the stock sub enclosure. this enabled me to get more bass but keep everything looking stock, however after more than 9 months and 12k miles the bose' quirks finally got to me and i replaced it with a much better deck.

 

I'm running one amp, 7 speakers, and a head unit and I garuntee it blows away mosts people's custom stereos in sound quality. Sure I don't have 2 12s pounding 145+ dbs but I garuntee my 135+ dbs (estimated and will test after my HU comes in) is more then enough for a 350Z.

Here's what I have:
xtant x603 3 channel amp
Boston Pro 10.5LF sub
Boston Pro 6.5 front components (mounted in stock woofer location and the tweeters are mounted in the kickplates)
Boston Pro 5T ambient tweeters located in stock location
Nakamichi CD45Z HU (amber display)
No rear speakers
All stinger wiring

now the xtant amp is fairly large and although I've mounted mine in my spare tire well (with my sub) it could easily be mounted in the area behind the driver seat where the stock Bose sub sits. It is very large (22" long) but will give you super clean power and can power the whole car (even though it's a 3 channel amp, it has 2 extra passive channels to power rear speakers).

With some line drivers, you could very easily start with the amp and a sub and then build from there. I'm actually going to an Eclipse 8063 HU and probably upgrading the front speakers to Boston Reference Z6s but that's just to try and polish up my system (I'm dumping the old stuff into a different car of mine). I choose my system for 2 distinct areas: sound quality and size. I didn't want to weigh the car down with massive subs, extra EQs, or rear speakers (which I hate anyway), and with the removal of my spare tire I only added 3lbs to my car.

The key to getting great results is starting with great equipment and not scimping for low cost alternatives.