Stage 3
Show-Ready Under-Seat Enclosure for GM Trucks
Stage 3 is where the build goes from “clean” to “show.” This is a full visual + performance setup designed specifically for 2019–2026 GM trucks — with big front + side clear acrylic viewing windows, a blacked-out interior, and lighting that makes it pop under the rear seat.
If you want a setup that looks insane at night, hits hard, and still installs like it belongs there — Stage 3 is that sweet spot.
Fitment
Built Specifically for 2019–2026 GM Trucks
- Fits 2019–2026 GM trucks (under-seat fitment).
- 3D-modeled for precise under-seat fitment (OEM-plus install).
- Rear seat functionality remains completely factory.
- Designed to look intentional — not like a generic prefab box shoved under the seat.
Enclosure Specs
Internal Dimensions & Clearances
📐
Total Air Volume
1.88 ft³ total air volume.
🧲
Mounting Depth
5.45 inches.
Note: Actual depth may vary based on subwoofer magnet size.
Note: Actual depth may vary based on subwoofer magnet size.
⬇️
Woofer Clearance
2.25 inches from the bottom of the enclosure to the floor.
What’s Included
What Comes with Stage 3
📦
Custom Under-Seat Enclosure
Built in-house using CNC-cut panels and our proven GM under-seat design.
Designed for real output, reliability, and daily use.
🖤
Standard Black Vinyl Finish
Stage 3 comes standard in clean black vinyl for a premium OEM-plus look.
You can upgrade to color-matched vinyl to match your interior.
🪟
Front + Side Acrylic Viewing Windows
Big, clear acrylic windows on the front and side so the setup looks like a full custom build
instead of a hidden box.
🎨
Blacked-Out Interior (Painted Inside)
The inside of the enclosure is painted black so everything behind the windows looks clean,
deep, and finished.
💡
Internal LED Lighting
Built-in lighting inside the enclosure to highlight the window area and give it that high-end glow.
🌟
Underglow (Floor Glow)
Underglow underneath the enclosure so the whole under-seat area lights up and looks unreal at night.
🔌
Plug-and-Play Terminal Cup
Includes our custom 3D-printed CB Customs terminal cup so wiring is clean, reliable,
and easy to connect.
🔊
Optional Loaded Configuration
Sold unloaded by default. You can choose to add subwoofers and receive it
fully loaded and ready to drop in.
Performance
What to Expect
Stage 3 is built for customers who want real bass output and a setup that looks like a full custom build. It stays clean when you’re cruising, but it can get loud when you want it to.
Final impedance and power handling depend on your subwoofer choice (especially if you select a loaded option). If you want a matched amp recommendation, shoot us your sub model (or just tell us what you’re trying to do) and we’ll point you to the right setup.
Built by CB Customs
Craftsmanship, Lead Time & Warranty
- Hand-built in Weatherford, Texas — cut, assembled, finished, and inspected in-house.
- Built to order — lead time is confirmed after purchase.
- Lifetime craftsmanship warranty on the enclosure.
- Real support — help before and after purchase if you have questions.
Compare CB Customs Stages
All stages are engineered for real performance. The higher the stage, the more show-level details (acrylic, lighting, and visual flex) you get on top of the sound.
Overall look
Stage 1
Clean OEM-plus enclosure, no acrylic, no lighting.
Stage 2
OEM-plus with a single acrylic accent panel.
Stage 3
Full visual build with big viewing windows + lighting.
Stage 5
Full show-truck treatment with premium cosmetics and max flex.
Acrylic & windows
Stage 1
No acrylic.
Stage 2
Front acrylic accent panel.
Stage 3
Big front + side clear acrylic viewing windows.
Stage 5
Largest window + added internal acrylic bracing details.
Lighting
Stage 1
No lighting.
Stage 2
Optional add-on lighting (front accent).
Stage 3
Standard internal LED lighting + underglow underneath.
Stage 5
Full RGB lighting package with maximum glow and detail.
Finish
Stage 1
Black carpet standard. Vinyl upgrade available.
Stage 2
Upgraded finish with acrylic accent details.
Stage 3
Black vinyl standard + blacked-out interior behind the windows.
Stage 5
Highest level finish: layered materials + premium show cosmetics.
Pre-wired & install
Stage 1
Plug-and-play terminal cup. Easy amp connection.
Stage 2
Plug-and-play terminal cup. Easy amp connection.
Stage 3
Plug-and-play terminal cup + lighting integrated cleanly.
Stage 5
Bench-tested show build with max detail and final checks.
Best for
Stage 1
Clean daily driver, hidden bass.
Stage 2
OEM-plus with a touch of custom.
Stage 3
Daily driver that looks like a show truck (windows + glow).
Stage 5
Full platinum flex for customers who want the absolute top tier.
Quick rule of thumb: Stage 1 = clean. Stage 2 = clean + accent. Stage 3 = full visual build with windows + lighting.
Stage 5 = platinum, no-compromise flex piece.
Questions?
Still not sure which stage or setup to go with?
Shoot us a text or call at (682) 516-3358, email sales@cbcustoms.net, or reach out below with your truck year and goals.