Dump valve opening late or wastegate early?

[gandyRX]

took the rex out for a drive the other day, done the usual let it warm up for abit then drove it without boosting for about 5 miles, got to a nice long stretch and opend her up, everything was fine and it felt good so i gave so i slowed down and came back, boosting it again but this time the wastegate chatter sounded louder than normal and the dump valve was letting off later, literally as my foot comes off the accelerator the wastegate goes off, then about 2 seconds later the dump valve opens, it used to be instantly
 
so let it all cool down took the dump valve off and stripped it, seems ok little bit of oil round the piston and trumpet nothing too bad though just normal, everythings intact, so cleaned it up and re greased it and put it back on but it still does it, checked the vacume and boost pipes all are ok so im stumped! boost is holding ok too still at 0.9 bar
 
its a 1993 gen 3 fd3s rx7 with a blitz blow off valve
 
any help would be good
 
cheers andy :burnout

[m1tch]

I get flutterdump with my Blitz blow off as well, not sure if you can adjust them, would be interested in the answer for this as well, mine seems to be ok when its cold, but when it warms up it starts to flutter dump

[CharlieP]

My Blitz BOV Flutters when letting off at about 0 boost....i.e. spooled up, but not really boosting much

[m1tch]

It might just be that my FC is running lower boost than an FD lol