Hi guys heard a few things about drilling holes in the air box to increase airflow through the engine but what size holes and where to drill them eludes me and what benefit would it give the engine has anyone tried this my friend had it done to a 1.4 pug 307 said it made a difference can anyone tell me anything more ??

You would be better off changing to a k&n or similar, but if you want to drill make sure you don't drill the wrong side of the filter, the trouble with drilling is you then allow warmer air from the engine bay into the intake therefore actually decreasing performance

Drillings a waste of time it wont make a difference what you could do is an iceman mod you get a cold air hose and remove the whole airbox you draw a circle around the cold air hose end onto the bottom of the box then cut it out with a dremel cutting 2mm inside the circle you marked you fit the cold air hose through this hole and silicone around the external join when dry refit and cable tie loosely the other end of the cold sir hose behind the pass headlight

Thanc for the advice guys i have a green cotton air filter in the cat and it has made a difference in smoothness in acceleration might just leave it at that then getting rid in a few months just wanted to make my focus bit more liveable it being. 1.8 tdci is sluggish have done all the usual nods egr blank etc

the only way to improve performance on the 1.8 tdci is by a remap. mines exactly the same and i cant justify spending £400+ for the remap so am happy to 'cruise' everywhere!