this is a very informative post!
I have been having the same problems myself but only pulling 7k! 6lbs of boost was hitting 1250* and only able to hold 55 -65. all the orange boots look ok, don't see any cracks but they are all soft like a sponge, is this normal? the intake boot is the softest. the left manifold looks like there might be some seepage. the strangest part is after a 6 hour battle, once I finally got north and stopped for dinner I got out of the truck and I always let it sit and idle for atleast 1 minute for turbo cool down, I notice the engine was a little louder and the exhaust sounded different. the ambiant temp was about 10 - 15 * cooler when I stopped but I don't know if that would have that big of an effect. after dinner we got back on the interstate and I ran right up to 80mph heading due east with a 30mph wind heading south east. my edge evolution cts programmer ( at pwr level 1 ) showed me 14lbs of boost and the egts were only hitting 1000* - 1100*. I don't know what or why this would happen or how. the motor only has 119k ( 3k of which I have now put on it ) miles on it and is only used 2 -3 times a year for dune trips and a couple into town so total about 3k - 3500 miles a year. I still have stock exhaust with cat but I have the diamond eye system on it's way. 3" dp, cat elimanator and 4" all the way back with no muffler. I hope this solves the problem but might only be a bandaid! if this doesn't work and changing the boots doesn't work I will be utilizing you info to construct my own methanol injection system, after seeing the online prices!
I am still following your thread to see how it turns out and if it fixes you problem, so keep the info coming and great job!
if anyone has any ideas about mine please speak up, I just can't stand an 6 or 8 hr road trip battle!