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Message: [QUOTE="Big Bore, post: 331934, member: 760"] A few weeks ago I was talking to Curtis after monitoring my EGT's climbing a VERY steep grade at around 9000ft elevation that has a speed limit of 50mph, which with 3:73's puts my RPM's very low in OD (I think it was 1750) which in turn will start bringing the EGT's up even running empty. Boost at that speed is only 5psi, but it's not lagging at all, I can accelerate at will with minimal throttle input. If I run the same grade at 60mph, EGT's are not a problem and I start hitting that sweet spot. Tunes are not the issue at all, even at the low RPM I need only about 1/3 throttle and there is no smoke. As an aside, being able to hold that RPM in OD on that grade is really a testament to Curtis tuning abilities. I am constantly amazed at how well this truck shifts and drives. I use the same tune (HOT) for everything, and the way everything is scaled the shifting responds to the load and throttle input seamlessly whether empty or loaded with 5 cords of wood going over Hoosier pass on switchbacks. All this with Swamps 175/30's. Bigger nozzles would definitely make a huge difference as proven by Curtis, and that is definitely coming soon. Anyway, the discussion shifted to compounds. It has always been my impression that compounds allow you to keep EGT's down in a situation such as the one I'm describing because the atmo would be pre-stuffing the drive turbo, making up for the lower atmospheric pressure at high altitude, and that at 1750 rpm the 38R is still making some boost and could spool the atmo without creating lag. Curtis was concerned there would be more lag than with a single because the atmo would be causing the drive turbo to lag while trying to spool the atmo. This is exactly why I keep going back the idea of a 4202, or an S series equivalent (DzChey tried to steer me towards an S series awhile back and I'm coming around to the idea) with a very loose exhaust housing as an atmo. I've been going through Cheyenne couple times a month, I need to stop by Dz's and buy him lunch and pick his brain I think. In any event, I thought compounds were a way to help[I] prevent [/I] lag and the accompanying high EGT's, not cause it? [/QUOTE]