Unfortunately this seems to happen to a lot of tuners. Awhile ago I dealt with a local tuner that followed this path. Never ends well for either party.
Yeah you really have to take tuning with a grain of salt. Even the best, have issues with certain setups. The only thing in Shaun's defense, is his tunes are very solid now. He owned an early 2011 GT and all his tunes were based from that car and all the dyno/track/street tuning he did. He was also the first into the 10's N/A with very light mods iirc.
Again, I helped beta test so many of his tunes here for him, along with a guy in Louisiana. That was before he got big on SVTP and started selling like crazy. Thats all he had too was a badass coyote tune for the manual cars, and the idle lope tune to go with it. It was completely different than the Lund tune, and Shaun was also one of like 3 tuners in the country that figured out why the #8 cylinders on the coyote was torching. His tunes were always safe from that huge issue, but not Lunds.
Lunds tunes were first to market with the lope, and the tunes were shot out setup like their were tuning the 4.6's. And with every first to market tune, all the little guys grabbed the value file from SCT that Lund did, and sold it. And many coyote's died from it. Shauns tunes were very tight and he would only sell you a tune if you sent him before logs of your car to make sure it wasnt already hurt. THen before he would dial you in after your initial mail-order tune, you had to re-log again after and send those in. Then he would send you a final tune and it was balls out. My 2011 GT/CS sang. That car went 12.1@117 on a bald DR only. Paper filter and all.
And as I dont agree with what he did, or his attitude to current and future customers, you really cant go wrong with his Coyote tunes. They are dialed in for boltons.