I have just read through this thread with interest. My Slide highflow done the exact same thing 6 months ago. Exactly the same situation, turbo was pretty new, had done approx 1500kms, had a proper, full power fc dynotune with z32, injectors, fmic, full exhaust, cams everything on 16psi and about 300kms later, one night it just let go. Boosted up then pop, no boost and grinding noises. I babied it home and pulled everyting apart and the pics are below. Nothing had been pulled apart prior so if there was something in there it would have been sucked through already. And it had a full filter setup so absolutely nothing could of or did go through it.
Yet when I tried to get it fixed under warranty, the owner Sheldon (because Aaron was uncontactable for prolonged periods) who builds the turbos said something must have gone through it or it overboosted. My car has the power fc boost control kit and was only running 1.1 bar and did not overboost nor did anything go through it. After being promised it would be repaired asap and within days it took weeks and they would not return my calls. After I finally drove down to see them face to face again I ended up paying for the new compressor wheel because they would not give me my turbo back until this happened. I was not happy. I have read many happy stories of people with these highflows but I personally will not be buying one again.
Here are the pics. That is just my story. Cheers