Posted for "George Braly" <gwbraly@gami.com>:

 Mike,
 
  
 The BSFC min for the big bore TCM engines is often as low as  0.380 to
 0.385,  rather than the 0.41 to 0.43.
  
 The 0.41-0.43 numbers are applicable to many of the TSIO-520x series
 engines and Lycoming TIO engines.
  
 The TSIO-550 does around 0.40
 The  TN IO-550 does around 0.385
 
 Regards,  George