The A90 Supra shares its platform with the BMW Z4 — which means the JBL factory audio system is the same as the Harman Kardon BMW fits to their roadster. It's a reasonable system overall, but the subwoofers are its obvious weak point. Soft, lacking definition, and mounted in plastic housings that resonate at the exact frequencies you're trying to reproduce. It's one of the more common complaints from Supra owners who care about sound.

The fix here was targeted rather than wholesale. The factory JBL sub units were replaced with Match UP W8BMW-S slim subwoofers — a direct fit, designed specifically for the BMW/Supra platform at 2 ohm to give it even a bit more punch. No modification to the mounting locations, no adapters, no wiring changes. They run from the factory JBL amplifier and integrate cleanly into the existing system without any DSP or additional processing required.

The more involved part of this job was the acoustic treatment. The plastic subwoofer housings were fully treated with STP BiPlast 15 which eliminates the resonance of the plastic mounts. Without this simple step the whole job would be meaningless. The floor area surrounding and beneath the sub locations received ETON NoiseKill a multiple layer sound deadening material popular to be used in sports cars - not as heavy but does its job perfectly. The combination addresses the resonance problem properly rather than just masking it with equalisation.

That being said, the system has been equalized using the factory head unit EQ, too, to make is sound as good as possible.

The result is tighter, better defined bass from the factory amp and due to the little tuning also overall sound improvement— and a cabin that stays composed when it's asked to work hard.

And yes — it's a Supra. It photographs well.

Equipment:

• Match UP W8BMW-S — 2-ohm slim subwoofers, direct BMW/Supra fit

• ETON Noisekill — floor deadening, sub surround area

• STP BiPlast 15 wave — plastic subwoofer housing treatment (essential part if you’re doing this job yourself)

• Factory Toyota/JBL amplification retained, tuned only with the OEM EQ