Need Advise Please Help!

[nemo]

A few months ago i replaced my turbos on my 32 gtr, i hav garrett 2860-10`s. But now i am getting a boost reversion/surge but really i got no idea what it could be ive replaced the bov`s cos i thought that the new turbos being bb were creating alot more pressure and was forcing the bov`s to open and close but turns out it didnt fix my problem, is it possable that the dump pipes arent flowing well enough and forcing gases back through the turbo? ive had it looked at a number of times but my mechanic and they`ve really got no idea why its doin it, they`ve suggested that a murge pipe in the exhaust manifold may fix it but i wanna be certain it will fix it as it`ll cost heaps to do and i dont wanna get it done to find out it achieved nothing, the car is still drivable but its bloody annoying and is robbing me of valuable boost pressure, when crusing at around 100-110 plus kph it sounds like the bovs are opening and closing but obviously it isnt them due to me changing them even tried a stiffer spring yet still no luck.

So if anyones had the same problem or knows what will eliminate my annoying problem can u please let me know what i should do i would be very appreciative

Thanks