⟲ 360° — drag meThe facts.
| Brand | Akrapovic |
|---|---|
| Part number | S-K4MET8-BNTA |
| Fitment | Kawasaki KX450 / KX450X (2021–2023) and KX450F (2019–2020) |
| Line | Evolution Line (Titanium) — complete system |
| Weight | 3.1 kg (stock 4.3 kg, saving 1.2 kg / 27.9 %) |
| Power | 53.8 PS (stock 51.8 PS, gain 2.0 PS at 9,850 rpm) |
| Torque | 44.6 Nm (stock 43.2 Nm) |
| Naming | KX450F and KX450 are the same motorcycle — Kawasaki dropped the F in 2021 |
| Road approval | None — closed course competition use only |
DescriptionThe whole story▼
Two full horsepower and 1.2 kilograms. Of the motocross systems in this catalogue, this is the one with the largest power gain — 53.8 PS against a standard 51.8 — and it covers five model years across two different names for the same motorcycle.
Key Features
- Titanium complete system, 3.1 kg instead of 4.3 kg
- 53.8 PS at 9,850 rpm, two horsepower above standard
- Torque up from 43.2 to 44.6 Nm
- Covers the KX450F of 2019–2020 and the KX450 / KX450X of 2021–2023
- The strongest power gain of the motocross systems here
KX450F and KX450 are one bike
Kawasaki dropped the F from the name in 2021. The 2019 KX450F and the 2021 KX450 are the same machine under two names, and Akrapovic lists both against this part number. If your bike is a 2019 or 2020 it will be badged KX450F; from 2021 the same bike is a KX450, and the KX450X is the cross-country version.
We have tagged all three names so the bike is found whichever one you search for.
Two horsepower on a 450
On a 450 motocrosser two horsepower is a real number rather than a rounding. The peak moves to 9,850 rpm and the torque curve comes up with it — 1.4 Nm more, which on a bike that is short-shifted between ruts is felt more often than the peak is.
The weight saving of 1.2 kg is the other half. Combined, they are the reason a full system costs what it does against a slip-on.
Not for the road
Closed course competition only. No EC or ECE approval and no homologation document. Akrapovic states it plainly and so do we.
What a motocross exhaust has to survive
A road exhaust lives a sheltered life. A motocross system gets landed on, kicked by a boot at every start, buried in mud, pressure washed while still hot and then left wet in a van. Within a season it will have been hit by roost from the bike in front several thousand times.
That is why the material matters more here than on a road bike, and why Akrapovic uses a welded bracket rather than a bolted one. There is no fastener to vibrate loose and no joint for grit to work into.
Repacking a motocross silencer
The packing in a motocross silencer degrades far faster than in a road exhaust — the gas pulses are stronger, the temperatures higher and the duty cycle brutal. A silencer that has lost its packing gets louder and can push a bike over a club noise limit that it passed a month earlier.
Akrapovic does not publish a service interval for this system. The practical answer is that a bike ridden every weekend wants checking once a season, and that the first sign is the note going harsh rather than the level going up.
Two names, one part number
Because Kawasaki renamed the bike in 2021, an owner searching for a KX450F system will not find one listed for 2021 or later, and an owner of a 2019 bike may assume a KX450 part will not fit. Both assumptions are wrong, and the price list settles it: one article, five model years, two badges.
Buying for an older bike
A 2019 KX450 is a used machine now, and a titanium system costs a meaningful fraction of what the bike is worth. The argument for it is that the system outlives the motorcycle: titanium does not corrode, the mounts are welded, and it can move to the next bike if that bike is from the same five-year window.
Article number
Akrapovic lists this system as S-K4MET8-BNTA. For the 2024 model year onwards the successor is S-K4MET9-FDHLTA.
FitmentWhich bikes this fits▼
- Kawasaki KX450 and KX450X (2021–2023)
- Kawasaki KX450F (2019–2020, the earlier name)
- Closed course competition use only
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