Cadillac CTS-V - Underdrive Pulley

What underdrive pulley did you go with?
Why?
Where did you get it?

Thanks.

Vette style Powerbond 10%underdrive pulley .

I do sometimes wish I just went with the 25% but its not worth changing again.

What underdrive pulley did you go with?
Why?
Where did you get it?
Thanks.

ATI #917278 (10% UD) for: (1) better harmonic damping on the 4" crank (2) minor parasitic relief via the 10% UD and (3) can be reconfigured with different pulley combos on same hub if so desired.

I believe Summit special order.