Crinkled french fries, discarded receipts, old gum wrappers — you probably have everything in the hidden corners of your vehicle except great bass. ThunderForm enclosures fill the nooks and crannies of your vehicle with low tones that stand out, but their factory look blends right in.

MTX engineers evaluate the "sonic signatures" of top-selling vehicles so they can design ThunderForms as custom acoustic matches. Each ThunderForm fits and blends inconspicuously into your vehicle, so you get great bass without losing any space. They're made of high-density polyethylene resin to curb resonances - they deliver bass that's tight, hard-hitting, and way down low. The airtight enclosure provides the correct internal volume to yield optimum bass response.

This enclosure comes without a speaker — you install your favorite 12" subwoofer. For best results, MTX strongly recommends using a speaker designed for an enclosure with a volume of 0.94 cubic feet. The enclosure mounts under the driver's side rear seat of select 2004-08 Ford F-150 SuperCrew and SuperCab pickups. The seat still folds up and down, and the jack stays in its factory location.

Please check with us before purchasing by using the vehicle selector on our site, or calling an Advisor at 1-888-955-6000 to verify fit information.

Product Highlights:

  • custom-fit black subwoofer enclosure for 12" sub
  • mounts under driver's side rear seat
  • fiberglass construction
  • volume: 0.94 cubic feet (sealed)
  • dimensions: 8-1/4"H x 34-1/21"W x 14-1/2"BD x 14"TD
  • mounting depth: 5-3/4"
  • warranty: 60 days
  • Our 60-day money-back guarantee

Hands-on research

What's in the box?

  • Custom-fit unloaded 12" subwoofer enclosure
  • Hardware
  • Installation instructions

Product Research

Features

Vehicle Compatibility: This Bass Slammer custom-fit enclosure is designed specifically to fit the 2004-2008 For F-150 Super Crew & Super Cab pickup truck

Note: Please refer to the Crutchfield Vehicle Selector to confirm fit for your vehicle.

Mounting Location: The enclosure mounts under the rear passenger seat of Ford F-150 Super Crew/Super Cab trucks. The rear seat will still fold up and down, while the jack remains in its factory location.

Enclosure Type: The sealed enclosure features fiberglass construction and fits one 12" woofer.

Tools For Installation:

  • Powered Screwdriver
  • #2 Phillips head bit
  • 5/16" Wrench
  • 7/16" Socket
  • T-50 Torx

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team — they open the box, verify contents, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

MTX Vehicle-specific Unloaded Enclosure Reviews

Average Customer Review:

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MTX Vehicle-specific Unloaded Enclosure

Written By jonH, manassas va on Tuesday, August 20, 2013

Crutchfield Customer Review (What's this?)

i purchased this box for my 12" rockford fosgate P3s for my 2004 ford f150 super cab (extended cab) because the box my sub came pre-enclosed in did not fit well in my truck, the price is a little steep, but the quality is great. for those of you that do not know, this box is not made of a wood, its almost like a hard composite plastic..but dont let that scare you. the box comes with the cables and ports ready to plug and play with slide on fittings, ( these dont work on push open release speaker wire inputs) so i cut them off stripped the wire and installed. this box did come pre-insulated and install was pretty straight forward, nothing tricky about it. now the sound quality in my opinion coming from this box is impressive, and made a big difference on the audio in my truck *** side note *** this sub is accompanied by a ken wood 1000 watt amp, rockford fosgate prime speakers, and the pioneer app radio head unit.

i would also recommend if you do already have a sub enclosure keep your old enclosure and hardware for future use this box is only going to fit in the specified vehicle application

Pros: fits snug under seat sound is great easy to install pre insulated/ pre ported

Cons: only fits my f150 and wont be transferable

Get everything you’ll need to enjoy your new MTX Vehicle-specific Unloaded Enclosure

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