MTX ThunderForms
1999-2001 Chevy/GMC
full-size extended cab truck

ThunderForms preserve all the legroom in pickup trucks and all the cargo space in SUVs. Each ThunderForm is an acoustically-designed, non-resonant, airtight enclosure, with the correct internal volume to yield optimum bass response from its subwoofer. So what makes ThunderForms different than a standard sub box? MTX engineers design each ThunderForm enclosure for optimum performance in your specific vehicle's acoustic space. Using state-of-the-art rotational molding techniques, and exotic high-density polyethylene, MTX creates a sculpted masterpiece of a sub box, beautifully finished to blend with your interior. And they sound as good as they look, delivering bass that's tight, accurate, hard-hitting, and way down low.

This MTX ThunderForm comes loaded with two premium-quality 10" Thunder6000 speakers and mounts under the rear seat of 1999-2001 Chevrolet/GMC Extended Cab Trucks (including 3-door models).


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 a particular vehicle, so the enclosure will fit properly in only one specific location.

Mounting Location: This enclosure is designed to mount under the rear seat of 1999-2000 Chevy/GM extended cab trucks, including 3-door models.

Tools Required:


Woofers: The enclosure has two 8-ohm, 10" Thunder 6000 woofers wired in parallel to provide a 4 ohm load


Special Notes

Warranty: The warranty only applies to the speakers, not the enclosure. The speakers normally have a 1 year warranty, but since the enclosure is designed specifically for the speakers, the warranty has been extended to 2 years.

Sensitivity: In the features and specs section, the sensitivity is automatically rounded down to 85dB. Actually, each woofer has a sensitivity rating of 85.1dB.

The new Thunder6000 series. With an oversized magnet structure, 2" four-layer voice coil and rugged NBR (Nitrile Butadiene Rubber) rubber surround, they're built to pump deep, low bass. Asymmetrical Linear Drive System (ALDS) combines a flat, progressive spider with an extended, vented pole piece to maximize performance and minimize distortion. The injection-molded, silver-machined cone is reinforced by 8 stiffening ribs for improved power handling (and great looks). Can you say "Bruiser?"


NBR Surround: The woofer is made with a one-piece NBR (Nitrile Butadiene Rubber) surround and gasket combination.  When bottom-mounting the woofer, the one-piece surround and gasket make an air-tight seal, to prevent any loss of performance due to air leaks around the woofer.  When the woofer is top-mounted, the one-piece surround and gasket combination enhances the overall cosmetic appearance of the woofer.  NBR has the added benefit of being resistant to ozone and UV rays for extreme durability.

Cone Cosmetics and Materials: The woofer cone is made of injection-molded silver-colored poly with 8 stiffening ribs for improved cone stiffness and higher mechanical power handling.  Concentric rings are molded into the cone and dust cap surfaces to give them a machined appearance.  "MTX Audio" is embossed on the poly dust cap.

Oversized Magnet Structure: This woofer has an oversized magnet structure, made with a 28 oz. Strontium Ferrite magnet.

Four-layer Voice Coil: A 1.5" four-layer voice coil is used for higher power handling.

Asymmetrical Linear Drive: This system improves linearity and permits high output with low distortion.

Extended Vented Pole Piece: The extended vented pole piece provides a more symmetrical magnetic field.

Enclosure Compatibility: This woofer can provide extended bass in sealed, vented and bandpass enclosures (see below for more information on enclosures).


Recommended Sealed Box Volume: The sealed box sizes recommended by MTX range from 0.13 cu/ft to 0.63 cu/ft.  The sealed enclosure MTX highlights on their spec sheet is a 0.38 cu/ft enclosure.

Vented Box Volume: The vented box sizes recommended by MTX range from 0.5 cu/ft to 1.0 cu/ft.  The vented enclosure MTX highlights on the woofer specification sheet is a 0.75 cu/ft enclosure.  One 2" diameter x 7" long port should be used with a 0.75 cu/ft enclosure; a 0.75 cu/ft enclosure with a 2"x 7" port has a tuning frequency of 38 Hz.

Single Reflex Bandpass Volume: The bandpass box sizes recommended by MTX range from 0.26 cu/ft to 0.47 cu/ft.  MTX highlights two bandpass enclosures on the woofer specification sheet.  One highlighted enclosure has an "S" value of 0.5, and the other highlighted enclosure has an "S" value of 0.6.  The highlighted bandpass enclosure with an "S" value of 0.5 is a 0.30 cu/ft enclosure, with a sealed chamber volume of 0.13 cu/ft, a vented chamber volume of 0.11 cu/ft and a single 2" diameter x 10" long port.  The enclosure with an "S" value of 0.6 is a 0.41 cu/ft enclosure, with a sealed chamber volume of 0.20 cu/ft, a vented chamber volume of 0.15 cu/ft and a single 2" diameter x 9.75" long port.

Note: The bandpass enclosure with the higher "S" value produces a more narrow bandwidth with better transient response; the enclosure with the lower "S" value produces a wider bandwidth at the expense of transient response.