Coles notes: '93 HDJ81 auto, 140,000km, 3" from OEM dump pipe back, no IC, Gturbo grunter extreme installed about 10 days ago, main fuel screw turned up 1/2 turn total in 1/8 turn increments, truck was running great, turbo spooled quickly, great midrange and top end power, EGT's in check. Took it on the highway yesterday, 32C, running about 120km/h, EGT's at ~900F pre-turbo (hit 1100F a few times when accelerating), came off the highway and turbo is slow to spool, runs 0-2psi at 60km/h where it used to see 5-6psi, only hitting 18psi at WOT when it used to hit 20psi set via MBC. Now if I stab the throttle the boost is slow to rise compared to before, no black smoke though, boost does still build but something isn't right, it's not like it was previously. I've checked the head to manifold and manifold to turbo bolts, all were still tight, no signs of leaks. The symptoms seemed to me like an exhaust leak pre-turbo might be the case, but nothing out of the ordinary. Turbo shaft has very little play and spins freely by hand. I'm at a loss, anything else I should be checking?