Ok, I just bought an ebay cold air intake and I want to use the k&n cone filter. So I hit up some local shops and there are a few different sizes of the cone filter, even the universal one. So how do I know which one will fit? The intake I bought is for a 99 Si, although my car is a del sol with b16.

 

just take the intake into the store and trial and error...

 

K&N has a lot of options on their website. You can size out the filter and get part numbers that come close to what you need. Save you a little time, and most dealers can order any of the K&N part numbers.