Long story so bare with me. Got 2016 truck that I deleted and tuned with ppei auto cal, exhaust and vas’s lift pump back in 2016 when the truck had 6k miles. Fast forward till a few months ago and guy calls and said he needed head gaskets and wanted to know if I would do it and I was busy and didn’t have time to. So he takes it to another shop the send heads off to be checked replaced gaskets with grade c gaskets and arp studs. Customer gets truck back and complains of low power. Took truck back to shop and they ended up swapping to another tuner adding wc fab y bridge and ic piping. And truck is still low on power. I talked with the guy who did and he has checked compression, check for boost leaks all the normal stuff. Well now the guy brings the truck back to me to see if I can figure it out. Truck runs fine it just lags and doesn’t make near the power it should. So customer wants to swap the turbo and I put a fleece 63 vat o. It. Still same result laggy, slow, and weak. No check engine lights, truck doesn’t smoke or anything noticeable. Any ideas would be great as I’m stumped