The cat-back for people who already went catless.
Most A90 owners hit the same wall. You fit a catless downpipe for the flow, and suddenly the car is louder than you wanted leaving the driveway at 6am — and droning on the highway at cruise. The usual fix is a quieter muffler that chokes the exhaust you just opened up.
The HKS Super Turbo Muffler solves it the other way round. It runs a full straight-through layout with no narrow points, so gas flows freely, then controls the sound through internal design rather than restriction. At idle it measures 61dB against the factory 58dB — roughly 5dB quieter than HKS’s own Dual Muffler, and close enough to stock that you can leave early without announcing it to the street.
Why it costs more than the Dual and sounds quieter
That is the engineering. It shares the same 85–70mm main pipe diameter as the Dual Muffler (31014-KT001) and the same free-flowing layout — the difference is the sound-control work, and that is where the cost sits. HKS certified it to Japan’s domestic noise inspection standard (JARI10200001P), among the strictest street exhaust standards anywhere.
Features
Full straight-through layout — no restriction points, improved exhaust gas flow
Sound tuned to remove highway drone, not just reduce volume
110mm dual brushed titanium tips
SUS304L stainless construction
Works with the factory exhaust valve — Sport and Normal modes switch exactly as stock
Specifications
Main material: SUS304L stainless
Outer tail diameter: 110mm dual
Main pipe diameter: 85–70mm x 2
Noise level (HKS): 87dB, idle 61dB
Noise level (factory): 85dB, idle 58dB
Certification No. JARI10200001P
Fitment
Fits MKV A90 / A91 Toyota GR Supra 3.0 B58, non-OPF models.
Choosing between this and the Dual Exhaust: take the Super Turbo if you are running a catless downpipe, park in a neighborhood, or cover real highway miles. Take the Dual if you want the larger 119mm tips and more volume. As an HKS MASTER Pro Dealer we stock both, and we are happy to talk it through before you buy.