Reading other tunes?

[nicstang]

I hope this isnt a dumb question, but if I have a car with another tune installed (Diablosport, Edge, SCT, etc) when I plug in HP, and do a "read entire", will it pull that tune, or the original stock file that was overwritten. A tech at SCT tells me that since their tune is simply over the stock file, all I will get is the stock file. Im thinking he's covering his butt so I wont even try to look at it.
The issue is a Tahoe with a Vortech blower bought used from a carlot and the handheld is not with it. Diablo (supplied the tuner with the blower) says I need to purchase another Predator to retrieve the tune. Im calling horsesh*t, but I also dont want an unrecoverable PCM.
Thanks for the input.

[APS]

I have edited these type tunes with my interface on GM's like yours without a problem.

However on some Fords I get checksum errors when I read the tune out. I haven't ever reflashed the Fords with the checksum error message using my interface, so this is not a blanket statement for all makes.

[383_Stroker]

I've personally pulled edge tunes from the ECM before, and HPT reads them just fine..

[ftsservice]

Yes, you can read them out, but there's a good chance you're not going to see all the parameters they changed if they used software other than HP to write the tune in it now, since not all software supports the same parameters. If its a Ford, you're going to be missing a lot of stuff since HP parameter support for Fords is lacking.