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Soundproofing Toyota Hiace
SPL Project

Preapretion to keep very loud bass inside

Identified Issues
Weak metall construction
Plastic too thin to keep bass pressure
Work Performed
Metal enhace with sutomotive sealant
Fullbody soundproofing
Dashboard soundproofing
Results
Metall shell ready fro 170+Db
No plastic rattling
27 packs Massa Bassa were installed

Dima is a very diligent professional
who tries his best to keep his customers happy and content.

He kept me up to date at all times. Highly recommend!
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Shadi Faraj

In this project we are preparing a brand new Toyota Hiace for an extreme SPL (Sound Pressure Level) competition build targeting 160+ dB. The first step is serious body reinforcement. We installed 350 kg of STP Massa Bassa vibration damping.

During the inspection we discovered that even a brand new Hiace body is very flexible — some reinforcement bars were already cracked under stress.

Photo Report of Completed Work

Metal weakness

All metal in the stock Hiace is weak, and even brand-new cars can have metal separation.

This is not acceptable for SPL projects — high sound pressure will eventually crack the metal.

Sika 300ml Black Sikaflex-252 Polyurethane Adhesive

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Bonds well to a wide variety of substrates
Capable of withstanding high dynamic stresses
Good gap-filling properties
Vibration-damping
Can be painted

Sikaflex®-252 is an elastic 1-component polyurethane adhesive especially designed for bonding large components in vehicle assembly. It is suitable for bonding coated metal, GRP, ceramic materials and plastics.

Increase metal strength

Here’s a clean, corrected version:
It required 40+ bottles of Sika automotive sealant to fill all gaps between metal panels.

Hydraulic pressure was applied to maintain the correct panel shape while the sealant cured.

Roof Soundproofing

For all metal and plastic panels, we used the proven solution STP Massa Bassa.

It increases panel rigidity by up to 4×, which is sufficient for SPL builds.

StP Massa Bassa Sound Deadening

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Need maximum vibration control for high-power SPL sound systems?

StP Mass’a Bass’a is a heavy-duty, multi-layer sound-deadening material built to handle deep bass vibrations and harsh road noise — ideal for professional installations.

Why it works:

Triple-layer build: aluminium foil top + bitumen vibration-absorbing core + adhesive base.
Extra-thick (4.2 mm) for powerful low-frequency vibration damping.
Designed for car audio — removes bass-panel buzz and improves clarity.
Durable & safe: works from –45 °C to +70 °C, humidity-resistant (up to 98 % RH).
Perfect for high-SPL setups or luxury restorations.

Side Walls Soundproofing

Here’s a clean, corrected version:
Side walls play a crucial role in SPL projects. If they flex, you lose significant dB in competitions.

By installing two layers of STP Massa Bassa, you eliminate this issue and make the structure extremely rigid — effectively bulletproof for SPL.

Doors Soundproofing

Even though SPL builds don’t require speakers in the doors, they remain a critical part of the car.

Stock plastic and metal resonate heavily, which negatively affects overall performance.

Doors Soundproofing

We install two layers of STP Massa Bassa to make the panels completely quiet and eliminate any rattles.

This also creates a solid enclosure, ideal for future audio upgrades.

Plastic Door Card

Since the original plastic is weak, we increase its strength by applying vibration damping with STP Massa Bassa.

Door Card Soundproofing

To prevent any plastic-to-plastic contact, the entire surface was covered with soft STP Biplast 10 mm.

This creates an additional protective layer, allowing the door card to sit securely — almost like on a pillow.

Dashboard Soundproofing

When dealing with loud cars, the dashboard plays a crucial role.

Even though it has multiple mounting points, it’s made from weak plastic and wasn’t originally designed to handle extreme vibration levels of 160+ dB.