Simply put, I have a volant CAI on my 98 5.7. The filter is actually smaller than my stock filter. Not by alot but it is smaller. Its the cprrect model for my truck and everything else fits up perfect. It has an annoying "whistle" sound on cold starts but goes away after about 20-30 sec. Maybe its because its cone shaped? Ive done a few other minor mods and the truck has more power than ever. No problems with drivability or acceleration. It just seems strange that my stock filter is larger. Im wondering if this is affecting performance or fuel economy.

 

Your whistle is probably coming from the elbow on the top of the throttle body. You have o-rings that are probably not sealed/seated correctly???

The filter size isn't an issue as the gauze style filter "flows" better

Only you would know if your fuel economy is better or worse?

 

on most vehicles with a CIA you will hear the whistle. the filter being smaller isnt prob a big deal as long as you keep the filter clean, from my understanding the aftermarket filters breath a little better so whats lost in size is made up by how "well" they breath.

 

thanks for the replys guys. i get 14mpg in town and about 17-18 on the highway. like i said power is better than ever....ill check the throttle body. i worry about stupid stuff like this so im glad somebody can help me out...thanks again guys