This might be completely dumb or irrelevant but here's my issue with the IX bov I put on my Evo VIII.

ok bov sutters gradually getting quieter but that's because I'm assuming this is a recirculating one vs my crap bov that just dumped the air back into the atmosphere right?

2nd...I dunno how I can explain this but when i'm on the throttle pretty hard esp on the highway and I gradually come off the gas, the release is very hard and the car gets very jerky...It's kind of annoying and know this isn't normal...any ideas bout what needs to be fixed or done????

 

sounds like a boost leak

 

a recirculated diverter valve will obviously be more quiet

do a boost leak test

ensure the orientation of your diverter valve is correct

 

^+1, make sure it's not on backwards. You'll get a lot of fluttering and boost will not hold.

 

This is why I gave my E9 valve away and put the stock plastic one, back on. It became very annoying after a while.

 

I assure you that's not a normal occurrence