Flash back to stock SCT Xcal 3

[Sinclaire]

Hey everyone, need some help please. I had my bf mkii turbo tuned some 7 years ago, I have left it on the highest tune this whole time. The other day I flashed it back to stock before leaving the car at a mechanic. The car definitely has less power and throttle response is not as sharp, but it doesn't feel and sound like it was before the tune. I can still hear the turbo whistle and the boost gauge is going over 10 psi, it also has a pretty loud flutter out of the bov when backing off. It was quiet as when stock. The car is stock other than a tune, hole cut in air box, that's all. I followed the promps on the xcal 3 for "return to stock". The procedure went perfect. Is it possible that running on a tune for so long has changed things in the car? Do I need to reset the ecu? Any experience or advice is much appreciated. Thanks.