Jerry, thanks for the great response above. I hope InMotion sees this thread and chimes in too.

Can you tell us some of the things that you modify - or should I say account for? (kind of a check list of benefits)

Such as:
Altitude
Octane of Gas available
Redline (RPM limit)
Top speed limit
Throttle map
Fuel map
Modifications (CAI, pulley, etc)

The reason I ask, is I want to know what I information I can tell you (or any other tuner for that matter) that will allow you to tune my car better.

I've seen mention of data logs. Should I send you a data log along with my ECU? Would it help? I have an OBDII connector and laptop with logging software. What readings would you want logged?

Thanks again for your participation in this forum. We appreciate all the info.