Nova 353 Vs Nova Flash 12:
Both are pretty much the same, the Flash 12 having better bottom less top, the 353 with the opposite.

RB T10 Vs T10RC:
Im not entirely sure on this, but the T10RC is like the 353 in terms of that Vs the T10.

I have the T10 with 2659 short conical header, and it's a real screamer even though I really need to run a medium or long one. It has heaps of power and is 100% definitely quicker than a Nova +12-SCT. Ive run about a litre or more through my T10 and it still pinches up on me.

So go for the T10 or T10RC, either of the two will ROCK YOUR WORLD!