actually, i think this comment is the most pertinant answer to OP's question. OP if youre wondering why youre gonna pay that much for a proper dyno tune, its simply for this reason. its the amount of diagnosis and feedback that goes into your ECU that makes the difference. a mailorder tune is basically just slamming a tune into your ECU that has worked on countless engine in the past and had *few* issues. its all preset stuff and assumes all your engine and sesors are 'in-spec' which more often than not ISNT the case. a proper dyno tune will take a good couple of hours labour if everything is running perfect. youre paying the mechs' basic 80 bucks per hour, plus a helper at 80 bucks per hour, plus the cost of a dyno, and a GOOD dyno can run up to the $MIL, but average at say 2-$300,000, plus electricity, plus advertising etc. in that time they will run through every single cell in every single table on your ECU, and take my word for it, there are a LOT of cells in a LOT of tables. at the end of a dyno you drive away with a car running as efficiently as it possibly can, and as a result you get a sheet telling you they were able to make a fictional horsepower figure so you could show off to all your mates, plus in the meantime got a solid stable AFR and the engine didnt blow up.