I read some where before that you shouldn't put holes in the air box. It will make performance worse rather than better. I think it was because it takes in hot air from around the engine bay rather than from where it's meant to be.

My car is a petrol but the air intake runs right across the front of the engine bay from left to right. Don't know if that helps.

 

Don't, it's not worth the hassle. Plus holes will whistle as they draw air. It was an old trick with some Vauxhalls (I used to tweak them), and while it gained you some engine response, you did have to make sure the holes were big enough to not make noise.

 

Really the only option if you want to alter the air intake for better performance is to fit an aftermarket kit from the likes of K&N rather than the standard replacement elements which they also make. That being said, I have a K&N fitted to the standard airbox and can confirm that I get about a 10% improvement in overall MPG, coupled with no increase in noise levels.

 

Really the only option if you want to alter the air intake for better performance is to fit an aftermarket kit from the likes of K&N ,,,QUOTE]
you then get on to pulse tuning of the inlet manifold which is only really effective over a small rev range or you have the variable length inlet manifoid as the 1.8 petrol has with all the idle air runner and it's associated problems ~your safe I won't start on the maths & theory

 

Hi Guys

Thanks for the info. I dont think Ill bother then lol.
Just find it a bit frustrating that there is limited tuning accessories for the c max, even at the ford show on sunday there wasnt much there if any thing. Stainless steel exhausts are a good power gain but expensive....

Cheers