Hello, 

 

Looking at swoping standard air filter to k&n air filter (panel). i have zetec s 125bhp  would you notice any performance/sound  differnce ? 

not sure if its worth the £45 yet to swop :)

I swapped mine out. Slightly more sound, maybe. Mountune identified the filter as a restriction, so it should improve performance. 

The only disadvantage I'd say for a K&N filter is that the oil which you have to put on it can go through the engine

Recently put one in my ST, better low RPM response and slightly better MPG. Engine does sound a little different. One thing I noticed after removing the filter from the packaging was metal debris, its made from a wire mesh. So do inspect it first before putting it in.

Again mines on an ST but I noticed a difference in sound more than anything. You could hear the turbo dumps slightly better. I guess through sucking in more air 

14 hours ago, zain611 said:

The only disadvantage I'd say for a K&N filter is that the oil which you have to put on it can go through the engine

I think that would suggest over-oiling if that were to occur.

You could always try this Ebay number 142090553478