I run a Speed Passion MMM and Orion 160amp speedy and it is no quicker then a Thunder Power and Hobby Wing Justock combo at our club. 10.5 blinky class seems to minimise the difference in performance between low and high end speedies.
Batteries however do make a difference, to a point. On our big open outdoor track there is 2 tenths difference over a 16-17sec lap, between different packs in my collection. Get the best packs you can afford.