well i have been driving my car for about 6 months without an intercooler and i finally had the time to put it on. The bov was closer to the turbo and it made a nice pshhh sound.

Now, it is closer to the t-body (on the cold side of the intercooler), and it flutters when i shift now. Is this compressor surge?

btw, bov is off a dsm of some sort (metal not plastic one)

 

i think the presure droped form putting a fmi and your bov isnt opening enough what kind of bov is it?

 

what psi are you running? I had the same thing happen to me. My BOV always fluttered a bit, but once I put the IC on it got louder. It is b/c of the pressure drop for the IC. How much of a drop are you getting? I ended up opening my BOV up (not a dsm) and cutting a few turns of the srping off. Now it is blowin of fine.

Anyway, it probably isnt surge since the BOV was working before, it is jusst the sound of the BOV only partially opening.

 

the pressure wont drop, there will be a greater volume to fill so more air to have to push through the BOV, try 2 bov's, or a 50mm, you could even tap a hole into the inlet manifold closer to the head for a quicker change from boost to vacuum to operate the BOV

 

it is just a dsm bov, I dont know what kind?....would it matter if it is mounted upside down...ie instead of on top of the pipe...on the bottom?

 

Make sure the BOV is getting a good vac source. If its not getting the vaccum response like it should it makes the BOV "lazy" The shorter the vaccum line from the manifold to the BOV the better.