My 8.0 work route is my magneto loop and I just cruised today. I think I was motivated by being late, but I ran it at 8:12 pace. My avg HR wasn't crazy though -- 143 bpm . I even had a nice downhill mile in 7:37. Fun.
It feels like it's improved form that's helping me. I'm running taller, which tilts my pelvis back and gets it out of the way of my legs. I believe (hope, really) that I'm strengthening the right muscles just by consciously running this way. The barefoot thing might be contributing as well. I also have more snap in my legs, which I attribute to not doing any long runs. I'm inclined to just go on this way for a while and see where it goes.