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 speakers — you install two of your favorite 8" Type 1 subwoofers. For best results, MTX strongly recommends using a speaker designed for an enclosure with a volume of between 0.3 and 0.5 cubic feet. The enclosure mounts under the rear seat on the passenger's side of the 1997-02 Ford F-150 Extended Cab truck (the passenger side rear seat will not fold down).

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.