Sprint Filter P08 Air Filter for Road & Track – Triumph Street Cup (2017–2026) PM174S

Clip-ons and a bikini fairing change how a bike is ridden more than they change what it is. The Street Cup gets used in short, sharp bursts — out of a roundabout, up to the next one, hard on and hard off — and that is exactly the kind of riding in which intake restriction shows up. Not at peak power, which this motorcycle rarely visits, but in the transient: the fraction of a second between the throttle opening and the engine having the air it just asked for. The Sprint Filter PM174S is a dry polyester element that starts at a low restriction and is washed back to it, instead of drifting upwards between services.

Key Features

• The standard airbox takes it as it is: no modification, no remap, no paperwork
• 80 µm of filtration at 5,050 l/m²/sec — the standard P08 medium, made for road and track
• Dry woven polyester with no oil in it, so there is nothing that can migrate downstream
• About double the filtering surface you would get from another performance filter
• Washable and reusable, and built to stay with the motorcycle for as long as it lasts
• Two years of warranty from the day it is bought

Response is a transient, not a peak

Every measurement that sells air filters is taken at wide open throttle, held steady. Almost no road riding happens there. What a rider on a café-racer-shaped Bonneville notices instead is how quickly the engine answers a small opening of the throttle in the middle of the rev range, and a restriction in the intake tract blunts that before it costs anything on a dyno. The P08 does not add power to a standard engine — that claim is not honest — but it keeps the resistance the engine is pulling against low, and it keeps it there over the whole service interval.

The change nobody has to notice

The Street Cup was bought for how it looks, and most owners are careful about what they hang on it. This one is invisible: the element sits inside the standard airbox, the cover goes back on unmodified, the fuelling is unchanged and there is nothing to declare.

Care and cleaning

On a bike that mostly sees dry roads, an air line is the entire maintenance plan: aim it at the clean side, work outwards, and the element is back at the restriction it started with. Everything beyond that is a wash — lukewarm water, a mild detergent, rinsing until the water runs clear. Let it dry right through in open air afterwards; heat and flame are out, and so is any kind of oil. Refit the PM174S dry. The maintenance sheet is in the Downloads tab.

Fitment & Compatibility

Made for the Triumph Street Cup, 2017–2026. The same PM174S element covers five machines built around this airbox — the Bonneville T100 and T120, the Street Cup, the Street Scrambler and the Street Twin. The full list with model years is in the Fitment tab.