Yeah it was because of tuning... Anytime you ask a truck to make a ton of power with tuning it has the potential to fail... When the engine didn't fail at 800hp they decided to crank it up higher than anyone has cranked duration with TONS of timing, they were trying to pop it. 4000uS and 40* of timing did the trick. The truck hit its set points and KAPOW!
Previous guy said it was shitty tuning. Its not shitty tuning my friend. Hard parts failed, 100% positive with a built motor it would have held just fine. I highly dought they really used 40* of timing and 4000us, well maybe 4000us but not 40* of timing.