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MTX ThunderForms

Custom-fit subwoofer for select 2004-up Chevy Colorado, 2004-up GMC Canyon, and 2006-08 Isuzu Crew Cab trucks (Tan)

Item #: 236COLTFPR

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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 ThunderForm houses a rugged FPR subwoofer with a venting system that keeps it cool, so it'll handle the heat — even if you've got the volume cranked.

Made for your vehicle
This enclosure installs under the rear passenger seat in select 2004-up Chevy Colorado, 2004-up GMC Canyon, or 2006-08 Isuzu Crew Cab trucks, extending out in front of the cup holder. 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 subwoofer
  • high-density tan polyethylene resin enclosure
  • enclosure fits under the rear seat and in front of the cup holder
  • single down-firing 10" FPR 4-ohm subwoofer
  • power range: 50-300 watts RMS
  • warranty: 5 years (free repair or replacement for 2 years, prorated replacement for years 3 through 5)
  • Our 60-day money-back guarantee

Vehicle-specific enclosures with subs? Say what?

Instead of the usual sub in a box, the manufacturer creates a molded enclosure that fits perfectly into a convenient spot in your specific vehicle, housing a high-quality sub. Some enclosures even include a built-in amp, for the ultimate in stealth bass. The advantages? You don't lose much space (if any), your sub is perfectly matched to its enclosure, and your enclosure has a factory look that won't tell potential thieves you have an awesome sound system. Doesn't get better than that.

MTX ThunderForms Reviews

Average Customer Review:

2 Reviews

Worth every penny

Written by: T from T Desfosses on January 24, 2015

2004 GMC Canyon
Crutchfield Customer Review (What's this?)

Simply an awesome product. I had a hard time finding a way to put a good system in my truck without sacrificing comfort, space or factory appearance. Sound quality, construction and ease of installation are all excellent. After shopping around and the different options I decided to try it and can't say enough.

Pros: The speaked MTX provides is much higher quality than I expected. The enclosure merges seamlessly with the truck, you don't even know it's there...till you turn it on! Kind of wanted to whine about the price a little but honestly can't because I don't believe you could build an enclosure that both sounds this good and fits so well.

Cons: Upfront product information, subwoofer specs etc would definitely make the buying decision easier as it is a relatively expensive product.

Better than I could imagine

Written by: Buzr from AK on February 25, 2012

2011 GMC Canyon
Crutchfield Customer Review (What's this?)

I debated buying one of these forever, but I finally pulled the trigger. Free shipping definitely helped. It fit perfectly in my 2001 GMC Canyon Crew Cab. My front seats fully recline and it really is a perfect fit. I swapped out the MTX sub with a Polk MM1040 and talk about amazing sound. I really couldn't say more in terms of positives on the box and the sub as they are a perfect match. I also have to say that Crutchfield has been AMAZING in terms of their follow-ups and help, from before purchasing, to after receiving my items. Best customer experience anywhere for me, in probably a decade.

Pros: Fit, color, quality, sound.

Cons: I can't even nitpick to find a con. Oh here's wasn't free.

Hands-on research

What's in the box?

Download owner's manual

  • ThunderForm with pre-installed 10" FPR shallow mount subwoofer
  • Mounting hardware
  • Installation instructions

Product Research



Vehicle-Specific Custom Enclosure: This MTX ThunderForm enclosure is specifically designed for installation in select 2004-2012 Chevrolet Colorado and GMC Canyon Crew Cab models. Please refer to the Crutchfield Car Selector to confirm fit for your vehicle.

Enclosure: The ThunderForm enclosure is made of molded high-density polyethylene resin, which dampens resonance and is rigid enough to resist flexing. The color of the enclosure matches factory GM colors. It is a down-firing acoustic suspension (sealed) chamber.

Woofer: The ThunderForm enclosure is loaded with a 4-ohm, 10" MTX shallow mount FPR woofer.

Mounting Location: This enclosure is designed to mount under the rear seat and extend forward, under the cup holders, in front of the seat. The cup holders can still be used, the rear seat will still fold up and down, and the jack does not have to be moved. Note: The provided dimensions are taken at the widest points of the enclosure. Keep in mind that these enclosures are custom made to fit in this particular vehicle, so the enclosure will fit properly in only one specific location. Mounting hardware is included to bolt the enclosure to the floor of the truck.

Tools Required: The manual provides this list of required tools:

  • Powered Screwdriver
  • #2 Phillips Head Bit
  • Wire Cutters
  • 5/16" Wrench
  • 6" Bit Holder Extension
  • 3" Socket Extension
  • 18mm Deep Socket
  • 18mm Wrench
  • 3/8" Socket Wrench
Note: The manual provided is for both the amplified and non-amplified versions of this ThunderForm. Some of the tools may not be needed for this non-amplified ThunderForm.


5 Year Warranty Terms: 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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