i have 3 b/l systems Novak 4.5/Mamba 4600 kv/Mamba 5700 kv and a Novak XBR 8.5 on order, i get cogging with the 5700 kv, but yet no cogging with the 4600 kv, (most likely my setup to blame) but for the price its awesome value, and i would highly recommend them, and yes, the Novak 4.5 is super smooth, but for nearly twice the price..

the adjustability on the Mamba is also awesome.