so i've read around the forum, and it seems like i have a intake leak.
around 2500-3000rpms when my MCSa 05' is about to shift, it begins to hiss and stops once it does the gear change. it happens in 1st to 2nd to 3rd gears. so if all of this is true, is it a leak in my intake? or something else?

if it is a leak, how do i tighten my intake so that it no longer make these sounds?

thanks it advance!!

 

Stock or recently upgraded intake system? When I installed my Alta CAI, I was able to hear the actual "whoosh" of the air going into the throttle body. This sounds like a high pitched hiss. It is common in throttle body upgrades. Same in all my trucks, etc.

 

its a stock intake. no mods on the car at all.
thanks!

 

I am bumping this because I am having the same exact issue and it's driving me nuts. I currently have my intake system completely disassembled in an attempt to figure this out.

If anyone has any suggestions please post up! 2005 MCS stock intake. Hissing is audible from the drivers side of the cabin when ON throttle from 2500+ rpms and disappears between shifts.