Quote Originally Posted by Caleditor View Post
The 2004 factory calibration will work just fine. I have done several and NEVER been able to out run the MAF table. GM's GMPX built several trucks and they did not use a COS.

Are EFILive's COS speed density calibrations?
EFILive COS may be operated jut like an OEM OS - MAF only, SD only, or blended (OEM style). While you could run the OEM OS in MAF only mode (as long as you don't exceed the airflow limits), a well tuned SD configuration (or blended configuration) will yield a "sharper" tune, with better throttle response.