I just bought the pipercross because it was washable. I wouldn’t think a change of filter in a standard air box would result in much of a change in air flow, if any at all.
I did e-mail pipercross. They asked me some questions like how did I clean it etc.
They said “This is very unusual!”
They asked me where I bought it. I told them I bought it from their online shop and quoted the order number, month and year – I no longer have the receipt.
I’ve not heard back since. So I didn’t think I’m getting a replacement and I can’t be bothered perusing it any further.
So yeah, Hiflo paper filters for me. And if I am ever tempted by a fancy filter in the future I’d go with K&N. I’ve had them before and had no issues.