I have a couple of M-Speed modified Novarossi NSR5. Compare it to Novamax S5 I feel both have about the same top speed, but the M-Speed one have better linearity on the throttle control. Power output on the M-Speed is all through the range of the throttle control, while with the Novamax it seems that power would suddenly increase at 3/4 full throttle. I feel the M-Speed's smoothness makes the car easier to drive at the corners. However, for the M-Speed the bummer is to shelve out almost US$600- for a pop, but you get not only a fast engine but a piece of artwork....Just look at the inside of any M-Speed engine and you will appreciate the details of works performed.