Interesting as not one D8 in this area is making more than 8100. After I installed the PCV mine was working awesome. 8250-8300 all day long. Slowly started losing R's down to where is would lug down to 7200, found my rollers were shot, dealer got a whole new clutch for me. R's came back to 7900- 8000, but won't get anything more. I have tried different springs, dropped up to four grams in the primary, played with my helix, and none of it has helped at all. If you can tell me how to clutch around it I would LOVE to hear it, and would be eternally great-full.
I have only rode mine above 8000ft, so don't know about lower elevation clutching. when it had an slp single and 19/42 gearing i just had carls clutching and it worked great. AKsnowrider sounds like he has a better set up than that, and he is always more than willing to help, but he is at elevation also. BTW I don't know chit about clutching so that is why i just went with the kit and is why i said it seems pretty easy to clutch around some of the probs