I've got a ZX5 and i've installed both a Novak and a Nosram brushless into it without too much trouble. With the Nosram, I simply popped a fan in front of it blowing across the heatsink, no problem there. With the Novak, I had to mount the speed well into the middle of the chassis so that the height of the fan didn't foul the chassis. Still was ok though. The noram / lrp speedos are quite a bit taller then the Novak unit if you stand them side by side Without a fan on top, so my guess would be that a Nosram / Lrp brushless speedo With a fan mounted on top of the heatsink wouldn't fit.
For the record i much prefer the Novak unit too. Blue (or red !) is Not better
