AFE has an intake available for the 550, but was wondering if it would be applicable to the 545.
https://secure11.nexternal.com/shared/Store...et=products.asp

Tried a search, but didn't find anything.

 

The claims are:
-Increased horsepower up to 11.75 HP
-Improves torque up to 10.50 lbs/ft

AFE intakes are rather highly regarded on the m3forums. And many seem to prefer them to the K&N intakes.

For $375, the seem to be a bargain compared to the $1K plus for the dinan intake

 

do a google search for AFE and E90. There were mentioning some idle problems. Since I dont own one I cannot say if the claims are accurate or not but its worth reading about it. There is a reason for saying "you get what you pay for".