New to this forum. Think I may have the last 6.0 Avalanche to leave the line. But this post is about my 2003 4x4 Avalanche recently converted from the 5.3 to a GMPP LS376/480 and I'm wondering if this would be normal powertrain loss? Bad Dyno? or a tuning problem? I went from 480 peak at 5950rpm at the crank to 321 rwhp peak at 5350rpm and also lost about 100 lbs of torque.