I have a D15B7 engine and the shortram(aem) tubing size is 2 1/2",now the filter is filthy as hell and it's not the type you can reoil or whatever,so I was just thinking instead of buying a new K&N filter($50),i could just buy a new shortram with bigger piping,but which model do I get it from?the ones on ebay all look like the same size

 

2.5 inch is probalie the recommended size for ur car..so i'd just stick with it..but if u want just go to your local auto store im shure they'll have a universal civic 3 inch intake arm..and then pick up one of there filters too

 

i would get a good filter at the least