The z9000s? Bodda Bing Bodda Boom, zipp zipp Fast. Awesome with foam, and in gas racing throttle I would guess? But in rubber the JR8450 was better for me. A little slower I guess.
Been running it ever sense. And with lipos on the other side of the car the lighter servo is a plus. And just to put a plug out for JR. Ive been running the R1 sense its release. And Ive more than abused my 8450JR I've been running it for 7 years and thats no exaggeration. I could only recommend JR, And even though the z9000s is on the heavy side that mother is Lightning fast.
.06 on the rector scale.