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MTX ThunderForm Unloaded Enclosure

Holds a single 10" sub — fits 2007-up Chevy Silverado 1500 and 2500 Extended Cab (Black)

Item #: 23615EX10U

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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 black enclosure comes without a speaker — you install your favorite 10" subwoofer. For best results, MTX strongly recommends using a speaker designed for an enclosure with a volume of 1.0 cubic foot. The enclosure mounts under the rear seat of select 2007-up Chevy Silverado 1500 and 2500 Extended Cab pickups

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 10" sub
  • mounts under rear seat on the driver's side
  • fiberglass construction
  • volume: 1 cubic foot (sealed)
  • dimensions: 36-1/5"L x 8"H x 16-2/5"D
  • mounting depth: 5-5/8"
  • warranty: 5 years (free repair or replacement for 2 years, prorated replacement for years 3 through 5)
  • Our 60-day money-back guarantee

MTX ThunderForm Unloaded Enclosure Reviews

Average Customer Review:

1 Review

More reviews would help...

Written by: Tater from Virginia Beach on June 28, 2011

Perfectly fits under the rear seat behind the driver in my 2011 silverado 1500 extended cab, didn't even need to use the screws to keep it to the floor, just some double-sided sticky tape along the bottom to adhere to the carpet.

I had some trouble picking the right sub enclosure because of a lack of reviews, and for the price, this single-enclosed box for a 10" sub (I used a Sony Xplode woofer) gives some tight, clean bass inside the cab. Perfect for rolling through your neighborhood at 2am on the way home after a long shift, because the acoustics stay INSIDE the cab of your truck.

After talking with a crutchfield rep about the specs, he even sent me a more detailed picture of the box (installation guide) before I made the purchase. We shall call him "Bill" for the moment, since unfortunately I cannot remember his name. Thank you VERY much Bill, I would not have the sound system that I wanted if you had not helped me. I would have bought something much more expensive that would have been twice as difficult to install and configure, you saved me time and mucho dinero.

If you've got a silverado, don't spend $500 on a sub box that doesn't fit. This one is worth it.



Hands-on research

What's in the box?

Download owner's manual

  • Custom-fit unloaded 10" subwoofer enclosure
  • Hardware
  • Installation instructions

Product Research



Vehicle-Specific Custom Enclosure: The enclosure mounts under rear seat in select 2007 and later Chevrolet/GMC Extended Cab trucks.

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

Construction: The sealed enclosure features fiberglass construction.

Tools For Installation:

  • Powered screwdriver
  • #2 Phillips head bit
  • 6" Bit holder extension
  • 10mm socket
  • Socket Wrench


5 Year Warranty Terms: Starting January 1st, 2013, this product carries a 5-Year Prorated Warranty with the following terms:

  • Years 1-2: Products found to be defective in materials or workmanship during the first two years will be, at Mitek's option, repaired or replaced by Mitek at no charge. The warranty period does not renew, but continues on from the original date of purchase.
  • Years 3-5: The purchase price of an item which becomes defective after the first two years and prior to the end of the warranty period will be prorated and credited toward the purchase of a new MTX product. The amount of proration is determined by dividing the original purchase price by the number of months in the warranty period (60), then multiplying the result by the number of months remaining in the warranty period.

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 verify what’s in the box, 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.

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