I can say, the Ninjas do have good run time and they can last quite long. Break in takes longer than Nova & V Spec. Seems to be like the Axe Rossis. The build quality is very good. They do seem to lack some of power that I can get out of the Nova and Axe Rossis. My cobra pulled away from it when it ran in a truggy. The sleeves are a bit straight cut and raw. They really don't have any chamfers cut into the ports. I guess the next series maybe reworked a bit.