I see in your sig, you're running a TA-49. How old is it?
Signs of turbo going bad are ---
*Smoking.
*lack of spool/boost.
*shaft-play from front-to-back, or excessive side-ro-side.
*visible contact marks on the housing.
*blown internal seals (which can be replaced)
If you suspect a problem, then take the inlet pipe off, gently grab the shaft nut with pliers and try moving it front-to-back and side-to-side. If you see any signs of the shaft touching the housing while you wiggle it, then you've got a problem and need to repair/replace it.
The biggest cause of damage on a typical small-shaft turbo is the huge backlash of air that hits the impellers when you let off the throttle hard during a WOT pass. The "sneeze" sound you here is what causes this. It takes a lot of effort to train yourself not to do it as harshly.
BTW, per your sig, it's "hypereutectic". And, do you have 45# or 42# injectors? And, ATR makes the "Pitbull" chip. Just thought you might want to fix all that...
