Air induction

[thebigone]

Hi folks.
I am thinking of putting an air induction kit onto my 1990 325i rag top. In relation to the size of the intake pipe, is it better to go for a dia that is a close to the size of the air filter, blowing onto it, that is, or one that might be smaller in dia working on the principle that the air will be forced into a smaller pipe and better for the engine.

Thank you chris.

[goosiegander]

unless you are shielding the induction kit from the rest of the engine bay its going to loose you power, by all accounts unless you are binning the standard afm and going for a mass airflow conversion the best thing you can do is fit a k&n panel filter,

better than that fit a new genuine filter into the standard airbox and forget about it a couple of quid and no loss of power