Just curious on how this motor blew. This is NOT my motor, but rather a buddy of mine.

Setup:
Low mileage D16z6 from a local motor importer
Stock block
Stock head
Greddy 15g kit
DSM 450's
Crome

After we slapped on his 15g greddy kit, made a basemap, and took it for street tuning. At full boost on 5 psi's the head began to lift like crazy where overheating occurs. But as long as he stayed away from boost everything was good, so after a week ARP head studs and a new OEM head gasket came in. Tuned it again to 11 psi and ran it 10 psi daily AFR's were flat 12's to high 11's. We went to the track, and after the third run the dipstick shot out and oil was everywhere. Took the car back and did a compression test cylinder 1 and 2 were 150, cylinder 3 was 130, and cylinder 4 had oil inside of it and was 170. After 3 days since this incident ringlands gave out, motor lasted about 1 month. I was thinking it might be a timing issue, but haven't had a chance to look at the tune. Just curious on inputs on how the motor blew.