BAD SVT
Addicted CEG'er
It is entirely possible to get a high quality mail order tune. If your car is functioning properly, has a wideband installed, and is just in need of tuning....you can certainly have a tune done via e-mail. Two things are critical, clean datalogs and an experienced tuner. With those things, you can have virtually as much success as you would on a dyno. Virtually everything you could feel/see in person will show up in the datalogs in some way. A/F changes, tming changes, load, etc.
I believe the common issue had around here with mail order tunes is underlying issues that prevent the tuning process from working. IE faulty O2s, Vac leaks, ignition issues, etc. Those things make the datalogs the tuner is using unreliable.
To put it another way, I have never heard of someone tuning a relatively new, stock vehicle via e-mail and having issues. It's almost always somebody with a hand-me-down 3L swap, hackjob, or million mile car that runs poorly and things a tune will be a cure-all.
Well said