Dont touch it, tests have proven these to be very crap at filtering properly.
Another problem, a foam filter is treated with a tacky sticky oil to help catch dirt (cos the foam is so crap!)..it can contaminate your MAF sensor....a very nice bill to fix that if it goes dodgy!
From years of tuning experince, the best ive ever seen from a panel filter is only about 4bhp on a dyno, from a 275bhp cosworth.....and the old paper filter removed was 40k miles worth and black with dirt anyway!
I bet a clean OE spec filtre is no measurable differnce.
Ive also seen some very nasty looking turbo compressor wheels from people running so called "performance" air filter.
So for a very few if any BHP gain.....is it worth possible turbo / engine damage from dodgy filtration?
If you dont believe me, theres plenty of internet articles i can dig out...how do you think they can flow any better than paper filter?.....answer...due to the worse filtration thats how!
Choice is yours.
I know that id rather buy a few OE spec paper filters from Vauxhall to change every 5k miles for a similar price of just one of the "performance" panel filters!
"We’ve been saying it for years but it’s a message that doesn’t seem to have widely got through. Nine times out of ten, dropping an aftermarket filter into the standard factory airbox is not going to get you any more power.
Factory airfilters have excellent flow and they’ve also got filtration that matches the car manufacturer’s stringent criteria. Put a different filter in the box and not only will there be almost certainly no improvement in flow, there’ll also be an unknown decrease in filtering efficiency. That’s a pretty dumb combination to pay money for."
Very true about the MAF meter in my fiesta i had before the corsa, i burnt out my mass air flow meter by putting an induction kit on it , and giving it a bit of a thrashing, when the mass air flow meter goes, your car starts to choke on tickover and at about 3000rpm and also drinks fuel, luckily only cost me £117 trade to replace though