If it's purely for "never having to buy another air filter", then it's perfect.
If you want it for a power gain, don't bother.
I've had a replacement K&N filter since the first month of having the vehicle, simply to never buy another air filter again. Just clean it every now and then and all is fine.
Can't really say if it's more responsive, but along with the free-flow stainless steel exhaust the Pajero drives beautifully.
