I have the HB CP2 bell hiller on my blade CP. Great improvement in cyclic response and smooth collective. $23 with shipping from Helihobby.

No additional modifications, I still have the BCP main shaft/gear, still using the BCP blade grips, flybar/paddles, BCP CF blades.....bolted on with no changes including no changes to transmitter programming or trims.

Here is a list of parts:

EK1-0228 Center hub set (Quantity x 1) : 1 : 5.25
EK1-0229 Rotor head set (Quantity x 1) : 1 : 5.25
EK1-0231 Paddle control frame (outer) (Quantity x 1) : 1 : 3.74
EK1-0213 Bearing (Quantity x 1) : 1 : 2.80
EK1-0234 Pitch control link (Quantity x 1) : 1 : 1.87

Subtotal : 18.91
Shipping : 4.50
TOTAL : 23.41

Balsapr.com was $29 with shipping for the same exact parts.