I was thinking about cutting my fire wall behind the seats and making a fiber glass enclouser for a 10" or a 12" sub behing each seat. I would rebuild the fire wall when the enclousers were in place. It would be like the back of the enclosure and the fire wall would be sealed into one. It's hard to explain but I have it fairly planned out. I would have to move some hoses and the battery.

If I could suggest something it would be this:

The space is limited, you don't really want to cut into the firewall, and you won't have good sound with 1 10-12 on the passenger side. The best thing to do is to have a bandpass box, or a box that is ported to the inside of your car from the front trunk area. Not only is the bass, and kick better, but a soundstage that comes from in front of you is much nicer than one from behind you.

To answer your question I would choose a 12 inch Rockford, or MTX, they both have small depth woofers that would make it fit a lot easier.

Trying to design and build a bandpass box that sounds good and will fit in the front of the Fiero sounds like a pain in the butt!

Why not just build a sealed box that fits in the passenger side foot well. Theres just enough room for a 10" sub. Using a sealed box means you don't have to spend a bunch of money on a high power amp that you would need for a bandpass box.

I built mine out of fiberglass with a Rockford Fosgate 10" sub and a Punch 200 amp behind the passenger seat. Because of the small size of the car it sounds GREAT!!

How about a trailer with a live DJ? No really,I saw a setup once that really boomed in a Fiero,it was some expensive stuff too.They'd used a Soundstream Reference Series,dual voice coil 8" powered by an older ADS,400watt amp with a 55Hz cut.Sounded like at least two larger speakers.A smaller amp powered the mids/tweets.The 8 was(hidden) mounted under the dash on the passenger's side,facing downward,in a cabinet.I did a similar thing with less $ involved,using cheaper components

First of all the 8" under the dash is a Great idea. But if you want SERIUOS bass i would go with the trunk idea. Bass from the front makes WAY better sound quaility than behing you. The thing is that you will need a stereo shop do this it isnt easy. A local stereo shop where i live have did this twice once in a Fiero and once in a MR2. You use a bandpass enclouse with the ports directly going into the cab. It sounds bad ass and hit really high SLP's. Also for the guy who said that sealed boxes need less power than bandpass WRONG. Its thew other way around bandpass needs less then sealed, and ported needs the most. The stupid part is that bandpass can also hold the most power and ported hold the least.

I did sluppy 123s idea. Got a jensen subwoofer and it fits right in the spot up under heater core casing. Did a little cutting that cannot be seen from the outside on the front speaker frames and squeezed some pioneer 6x9s down in and just popped on the grills! Also cut some plastic in between seatbelts and rear glass and custom made boxes for another set of 6x9s that sink right in to car frame. Looks factory! When I get a scanner I'll take pictures and show you all.

I like the bandpass idea best, however where to put the ports into the car??? theres a brace ( on my car ) under the car thats in the way. And I can't see anyway up top unless you do some wierd stuff through the heater box.

Now that's a stereo system

Wow!! it looks nice!!

Unbelieveable SCCA! Not only do I not want to even show my system and the work I did, I think I'll save myself any embarrassment and just forget the scanner!!

LOL...this isn't my car. This is nothing but a full competion system. This guy spent some mojor bucks on this thing. Check it out....http://www.perigee.net/~lunapark/

hey Lynx, Bandpass boxes ARE ported boxes.
But anyway, I think putting subs in the trunk is a PAIN IN THE ASS but it sounds great when and if you finish. I know so many people who start the project but get too frustrated to finish. If you have a lot of time and patience go for, you won't be disappointed. If your like me and have little of both, just put a sub in the passenger footwell. Sounds good enough with about 2% of the hassle.

No yellowformula, A bandpass box is a BANDPASS box and a ported box is a PORTED box. There is a BIG difference. Yes they both use ports but and sort of the same way. The both use the ports as tuned whistles (figure of speech) but a banpass box uses a sealed side to force against to make pressure for the ports. A ported box just uses pure woofer movement for the ports. I should know this stuff i work at a Car Stereo Store.

Lynx is right about the type of boxes. If you have a crutchfield handy, they have a page with a picture of all types of boxes and how they work if you are interested.

Plus you don't have to spend the money that that guy spent on his, outside of the cost of the speaker it would only cost an extra $20-$30 dollars in materials as opposed to cutting your firewall and installing a box there.

Sluppy123,
My passengers like the footspace. :-)

My sealed box sounds much better with the window open about three inches,so is it a bandpass system?!,well,probably not but I had to think about it.I like sealed systems,with speakers that are meant for these,because the bass tends to break up a lot more gradually at the limit ,and you don't have to constantly mess around with an EQ.Had a box/12"CerwinVega,vented to the inside of another mid-engined car,won't do it again.If I'd spent the amount of money I did on better,smaller stuff,I would have had the same/better results(inside the car at least)and could have kept my trunk.I wonder if a bandpass in the floor,just in front of the seats would work,hole in floor only for magnet?Airspace under a slightly raised floor could be the "horn".

One cheap way of getting big base out of you fiero is to build two boxes for 8" speakers then connect them together.THe boxes would fit on your head and look like headphones.hehe..The picture of the box in the front spare tire compartment looks trick until water leaks in or you have to work on your brake system then it might be a pain in the hiney!! Ill post some pics of my fiero on here when my friend brings his DS-7 camera over this weekend!

WOW SCCA, that's one mean looking Fiero! I really love the interior! Ofcourse they made the wrong choice for their digital dash... ;)

I agree Cliff. If I ever decide to install digital gauges in my Fiero I am getting them from this place called Pennock Automation. Ever heard of them?? :)

Pennock Automation? Hmmmm, rings a bell... ;)

To LowGG, Your sealed boxes do sound better with the window(s) down becuse in a way you are creating a bandpass enclouse. You'll notice that if you close the window beside you and open the far one it will sound loud to you but quite to the other side. Theres lots of cool things about sealed boxes. Also mess with how open your windows are they will sound differnt depending on how open they are.

Well I built a custom box which covered the entier rear window. I had a plexiglass widow on the back and front of the box so I could see what was happin behind me. I mounted 2 10 inch subs in this box. They where each aimed at the back of the drivers head and passengers. The sound was great and it looked very custom. I covered the box with matching vynle and it fit so snug that I did not have to bolt the box down. My amp sat just below in the middle storage compartment after I removed the door. It took a little time to get the box to fit right but it is worth it. The total cost for the box was about 60.00 cdn. and it looked great. I plan on building another one soon.