There's so much more to quality tuning. The stock tune is a soot laden nightmare with all the extra injector cycles. A lot of wasted fuel and soot laden oil if it's not addressed.If all he is doing is deleting, it's really not that big of deal. There's tables for the EGR and a couple of switches for DPF and DEF. Then it comes down to deleting the correct DTC's which is what I've had a hard time understanding the workings on our ECM's. I tested one of the "auto-tuning" upload sites for EGR and DEF delete and the result was more or less the same solution as SFK and MR Tuning. I wouldn't be surprised if that's what he's doing.