Dont feel alone, my 09 d8 is the biggest pos I have ever had when it comes to runability. I have not been able to pull rpms no matter the clutch setup. Mine pulls 7850-8050 all the time. I can drop 10 grams of weight and the top end rpm will not change. I am currently running team silver primary 165-344 68 gram mtx with 2 grams in the belly, stock secondary helix 56-42-.36, team black white spring 160-260 with two derlin washers, and geared down to 2.27. With this setup it pulls hard in the low and mid range but quits pulling on top.I unload at 2500' and I ride mostly 4500-6500 feet. I also have slp single and lots of venting. I believe it still has a fuel map problem, mine is very lean in the middle and I am guessing way rich on top that is why it will not pull rpm. I am tired of spending tons of money on this thing and nothing helps. Now it looks like I will be buying a pc-v to try to get a map in this thing to make it run. I am also going to try a helix with a 38 degree finish angle to see if that will help with rpms and make it backshift quicker.
its gotta be rich cascade..with what your running you should be pulling 9000...that sucks bad..I hope you find the problem and it runs awesome after ...