TCM only makes 3 TSIO-550s, the B, C, and E.  The B and E are 350 HP at 2,700 RPM and the C is 310 HP at 2,600 RPM.  All the IO-550s and IO-520s are 8.5 to 1; and all the TSIO-550s and TSIO-520s are 7.5 to 1.

 

Like George said, the TCDS shows the TSIO-550C for the Columbia 400.  The web site is incorrect.

 

Mike Easley