It’s a question that’s been asked many times: are performance air filters worth it? Many decide to fit one regardless - after all, it’s just about the cheapest and easiest modification out there.
But to bring some science into the equation, the ever-analytical Jonathan Benson of Tyre Reviews has decided to avert his attention from the rubber hoops he usually talks about to wade into this long-running debate.
We’ve seen dyno tests like this before, but what’s interesting here is Benson has used two different cars for the job - an E92 BMW M3, and a Skoda Octavia vRS. So, we can see the effects of fitting a performance air filter to a reasonably exotic naturally-aspirated V8, and a fairly run-of-the-mill turbocharged inline-four.
On the BMW, new and used K&N filters, a carbon fibre Eventuri intake, a standard paper filter, and no filter at all were on the testing menu. The Skoda was also trialled with a paper filter, along with Pipercross and RamAir aftermarket filters.
The conclusion? We’ll let Benson give you the minutiae, but suffice to say, there’s a reason the performance filter question hasn’t ever been fully answered - because it depends. How well the standard intake system has been designed plays a big factor - one of the cars tested showed no meaningful power increases.
It’s also worth pointing out that installation matters. If you don’t make sure your new performance filter has a good supply of cold air, the power figure might actually drop. So, you potentially do have something to lose by fitting one of these.