I have a 2.75 inch AEM SRI well i bought a new filter with rubber things and clamped the .25" and it was on there but it just didnt seem right i know that sounds stupid its such a small difference but it didnt sound right it ran okay tho. Well i went online and got the right size filter and its WAY better. You can do it and it might not even be any difference it all might have been in my head. Yeah i hate that though have 3" everywhere but 2.5-.75 are HARD to find..