I recently added headers, high flow cats, x-pipe, and a boss intake. I already had a tune and a cold air intake. After installing headers and boss intake I now have a a high pitch air whistle noise at 1500-2000 rpm. If i give it more gas I can't hear the high pitch noise anymore. So I thought I had some kind of vacuum leak, so I smoked the intake and found no leaks, it is driving me crazy. I think my gas mileage is a bit worse also, I am not sure though, I drive it pretty hard most the time, but my last tank got less than 200 miles. I guess I am wondering if anyone has heard any different air noises with the boss intake or has any ideas on what could be causing this noise.

 

Hmm that's weird. Usually a vac leak won't whistle, and an exhaust leak will flutter. Not sure, but of topic, do u have mastiffs? I have three bull mastiffs.

 

It's the cai. I woud bet money on it. I'm not sure why it didn't happen before the headers and such but my last mustang had the same thing going on. Never really bothered me so I never cared to find the issue but once I went back to stock to trade the car the noise was gone.

 

Yea, I raise english mastiffs, been breeding them for 12 years. Their awesome dogs.