The HKS Hi-Power Muffler (part 31006-BF002) is a full cat-back exhaust for the 2022-2026 Subaru WRX (VB chassis, FA24 turbo 2.4L). HKS calls it a "muffler," but it's a complete cat-back system, not just a rear section. It replaces the factory quad-exit setup with a single, right-side bullet-style exit and runs 85mm (≈3.35") straight-through piping versus the roughly 60mm (≈2.36") restriction in the stock system. The Hi-Power name is one of HKS's oldest exhaust lines — it's been on Subarus, Hondas, and Nissans for over two decades, and it has always been about a deep, aggressive tone rather than max-decibel screaming.
Real specs (no marketing spin)
| Spec | HKS Hi-Power 31006-BF002 |
|---|---|
| Fitment | 2022-2026 Subaru WRX (VB, FA24 turbo) |
| Type | Full cat-back, single right-side exit |
| Main pipe diameter | 85mm (≈3.35") vs ≈60mm stock |
| Exit / tip | 119mm (≈4.7") with adjustable slide-out tail tip |
| Peak power gain | up to +11.7 kW (≈15-16 hp) high-RPM |
| Torque gain | up to +14.9 N·m (≈11 lb-ft) mid-range |
| Weight | 13.0 kg (≈28.7 lb) vs 21.7 kg (≈47.8 lb) stock — saves ≈19 lb |
| Sound | ≈88 dB with inner silencer in / ≈100 dB silencer removed |
| Material | SUS304 + coated SUH409 stainless |
| Min. ground clearance | 128mm (≈5.0") |
| Emissions | Keeps all factory emissions equipment intact (no cats removed) |
| Price (Kami Speed) | $1,199 — on sale $1,079.10 (10% off) through the HKS June Promotion, ends 6/30 |
| Availability | Pre-order / special order — JDM part, plan on roughly a 10+ week ETA |
What actually changes on the car
Power: real, but don't buy it for the dyno
HKS quotes up to roughly 15-16 hp at high RPM and about 11 lb-ft of mid-range torque. That's a solid result for a cat-back that keeps the stock turbo and downpipe — but it is not life-changing, and you should be skeptical of any listing that calls it "massive." A cat-back's job on a turbo car is mostly sound and flow downstream of the turbo; the big power on an FA24 lives in the downpipe, tune, and intake. If your goal is numbers, this is one piece of a larger build, not the centerpiece.
Sound: the real reason to buy it
This is where the Hi-Power earns its name. With the removable inner silencer installed, it sits around 88 dB — noticeably more present than stock but livable for a daily commute. Pull the silencer and it jumps to roughly 100 dB with a much harder, race-style edge. HKS tunes the muffler to push the FA24's boxer rumble while keeping some of the crisp high-frequency note on top, so it doesn't go full raspy four-cylinder buzz the way some budget catbacks do.
Drone is the honest caveat. Straight-through, single-exit systems on the FA24 tend to drone somewhere in the 2,500-3,000 RPM cruising band — exactly where you sit on the highway. Running the silencer in tames most of it, but if you do long freeway commutes and hate cabin drone, go in with eyes open. This is a trait of the design, not a defect.
Weight: the underrated win
Dropping from 21.7 kg to 13.0 kg is about a 19 lb reduction, almost all of it behind the rear axle. Rear-biased weight loss does more for how the car feels turning in than the number suggests. It won't show up on a stopwatch dramatically, but it's a genuine, permanent improvement you feel every drive.
The look: this is the make-or-break
The VB WRX ships with a quad-exit rear. The Hi-Power converts that to a single right-side bullet tip. Some owners love the clean, JDM time-attack throwback; others think it looks unbalanced next to the factory quad bumper cutouts. There's no neutral answer here — decide whether you like single-exit on the VB before anything else, because the sound and weight won't matter if you hate looking at it. The adjustable slide tip at least lets you dial the protrusion to sit flush with your bumper.
Who it's for — and who should skip it
Buy it if: you want a deeper, louder boxer note with the option to dial volume up or down, you like (or can live with) the single-exit look, you value the weight savings, and you want a proven Japanese brand with reliable fitment that keeps your emissions equipment intact.
Skip it if: you're chasing big horsepower from a cat-back alone (you won't get it here — spend on a downpipe and tune first), you can't tolerate highway drone, or you specifically want to keep the factory quad-exit appearance. In those cases a quad-tip aftermarket cat-back is the better match.
How it stacks up against the field
On the VB WRX, your cat-back choices roughly split three ways. Stock quad-exit is quiet, heavy, and restrictive — fine if you want sleeper looks. Quad-exit aftermarket systems keep the factory four-tip appearance and tend to be a bit more conservative on volume. The HKS Hi-Power single-exit is the aggressive, lightweight, sound-and-stance play that leans old-school. None of these unlock meaningfully more power than another on a stock turbo; the real decision axes are look (single vs quad), volume and drone tolerance, and weight. Pick on those, not on horsepower claims.
Frequently asked questions
Does the HKS Hi-Power add horsepower to the 2022+ WRX?
Yes, modestly — HKS quotes up to about 15-16 hp at high RPM and around 11 lb-ft of mid-range torque on an otherwise stock car. It's a real gain for a cat-back, but it's not where the big FA24 power lives. For meaningful numbers you'd add a downpipe, intake, and tune.
Is the HKS Hi-Power loud, and does it drone?
It's about 88 dB with the inner silencer installed and roughly 100 dB with it removed. Like most straight-through single-exit systems on the FA24, it can drone in the 2,500-3,000 RPM cruising range. Keeping the silencer in significantly reduces it.
Is it a full cat-back or just a muffler?
It's a complete cat-back system despite the "muffler" name. It does not replace your catalytic converters and keeps factory emissions equipment intact.
Does it fit the GR86 / BRZ since they're also FA24?
No. This part (31006-BF002) is specific to the WRX VB chassis. The BRZ and GR86 use the naturally aspirated FA24 in a different platform and have their own HKS exhaust part numbers.
Will it change the factory quad-exit look?
Yes. It converts the stock quad-exit to a single right-side bullet tip with an adjustable slide-out tip. If keeping the four-tip factory look matters to you, choose a quad-exit system instead.
Is it street legal?
It keeps all factory emissions equipment in place. Cat-back systems are generally street legal in most states, but local sound/visual-modification rules vary — check your state's rules, especially in California.
How much is the HKS Hi-Power for the WRX, and is it in stock?
At Kami Speed it's $1,199, currently $1,079.10 (10% off) during the HKS June Promotion through 6/30. It's a Japan-built part that ships as a pre-order/special order, so plan on roughly a 10+ week ETA. Ordering during the promo locks in the discounted price while you wait.
Bottom line
The HKS Hi-Power is a sound, weight, and stance upgrade with a modest power bonus — not a horsepower mod. If you want the aggressive single-exit look and a switchable street/track volume from a brand whose fitment you can trust, it's one of the strongest character upgrades for the VB WRX. If you want big power or factory-quiet quad looks, look elsewhere. Buy it for the right reasons and it delivers.
It ships as a pre-order (roughly a 10+ week ETA on this JDM part), so if you want it, the move is to lock in the HKS June Promotion price of $1,079.10 — 10% off — before it ends 6/30, and let it build while you wait.
Get the HKS Hi-Power 31006-BF002 at the June promo price · See the full HKS June Promotion · Shop all 2022+ WRX (VB) parts