Re: K&N Open Pod
open pod means that there's no airbox - intake air is affected by the engine heat. you will lose low-end performance, but you will gain high-end, but only at the very high end (above certain rpms and definitely not daily drive, unless youdrive like a madman everyday).
there is a lot of discussion in other forums (e46fanatics, bimmerpost, e90post, etc.) on the pros and cons of installing an aftermarket air intake. some have even posted empirical evidence after conducting tests. go have read...
rodney (of r2d) and i have been doing some experimentation ourselves to improve the air intake, but with the stock airbox. we have even made prototypes and installed on our own cars. not ready to share yet until we get more feedback. do drop by r2d and have a chat if you want to find out more.