The 4 times I ran my zilla I started it with Circa's.... But it was just a "stock" motor. Fresh bore, rotted FMF the first time then an AAEN when I rode it the once and started it the other 2 times. I plan to have another big mill and y'all know me,,,, so this wouldn't be a bad deal at all! Or for the 350 Tri-Z mill,,,,