Sprint Filter P08 Air Filter for Road & Track – KTM RC 390 R (2018–2021) PM145S

The R is the version bought by people who read regulations, and that changes which questions matter about an air filter. Not how much more it flows, but whether it leaves the machine in the class it was entered in. Most production-based championships treat the airbox as a controlled item — the element inside may be replaced, the box itself may not be removed or reworked — and the Sprint Filter P08 was built for precisely that boundary.

Key Features

• Replaces the paper element inside the untouched original airbox: nothing removed, nothing modified
• Dry single-layer polyester, 80 µm at 5,050 l/m²/sec, serviced with compressed air
• Twice the filtering surface, near enough, of an ordinary performance element
• No oil, so there is nothing to reapply in a paddock and nothing to reach the intake tract
• 93.13 % of 100-micron particles held, against 76.42 % for four-layer oiled cotton
• A working life intended to match the machine's, covered by two years of warranty

What the rules usually allow

Wording differs between championships and clubs, so read your own set; the common pattern is that a free choice of filter element is permitted while the airbox, its inlet and its volume are not. That makes the element one of the few genuinely free choices on an otherwise controlled intake, and it makes a part that goes into the standard aperture on the standard fixings worth more than one needing brackets. Sprint Filter has spent time on the other side of that boundary too: the company was the official air filter supplier to KTM's Moto3 programme in 2014, 2015 and 2016.

Where the claim ends

It ends well before horsepower. A replacement element in a standard airbox adds no measurable output to a production machine, and a claim that it does would survive neither a dyno nor a protest. What it removes is a variable. An element cleaned back to a known state does not quietly change what the engine is being fed between one weekend and the next, and that is the only sort of consistency an air filter is in any position to offer.

Care and cleaning

In a paddock it is an air line on the clean side, blown outward, and the element goes straight back — nothing to soak, nothing to dry, nothing to reapply. Between events, hand-warm water and a mild detergent will take out what the air did not, followed by a thorough rinse and a slow dry in moving air. Heat is never part of it, and neither is refitting it damp. Look under Downloads for the PM145S maintenance sheet.

Fitment & Compatibility

The P08 for the KTM RC 390 R, 2018 to 2021. Nine machines share this element across KTM's first small-capacity generation; the Fitment tab lists them with their years, and the code to quote is PM145S.