They Work Great.
Used on Many Jegs Engine Master Challange Engines.
Many have won the Torque and Hp Contest with a TCI Harmonic balancer.
John Kasse is most Famous for using.
Ford Engines.
One Pontiac V8 he won $200k with a TCI Rattler.
I recall one home built Small Block Chevy Won with a TCI Rattler.
Most on forums vote for ATI Race Balancer.
Comes down to personal preference.
I have bought 2 TCI Rattler balancers.
One for the TA.
Another a 400 sbc for the 410 ci I have yet.