two bypass valves?

I don't see how an additional bypass would help. If the one is fluttering when boost gets to a certain level it will still do it when the boost gets to that level regardless of the presence of a second valve.

Are you running a standard Bosch type valve like this one:



If so, can you describe how it's connected? From where are you taking the vacuum reference? Which side sees boost pressure and which side is the discharge?

One more thing: If you are running that Bosch valve I can tell you it looks a lot like the stock diverter valve on my VW Golf GTI 1.8T winter beater/daily. A common upgrade on big- and even stock-turbo 1.8Ts is a Forge 007:

Forge Motorsport | Alloy Fabrication

I've got one on my 1.8T and it's a piston-type versus the Bosch diaphram. Mine came with selectable springs which is useful to minimize surge but hold boost. Might be worth looking into as an alternative to the Bosch one, if that's what you've got now...

is it fluttering under continuous driving or deceleration? mine flutters a little under deceleraction towards about 1500 or so... like it will release the pressure then it will get quiet then ill hear a little fluttering noise...mines not too lout though, but ive been in other cars that have fluttered too so i just ignore it..... my buddies did it in his turbod gto, then he got a better wastegate and it stopped...but that was also a turbo car, and yours isnt so idk...

cant you cut springs in bypass valves to help them release better under higher boost? or did i read that wrong?

and yeah, ive never heard of running 2 either