The tuning costs $80 and it was another $16 return USPS shipping. Go to this link to see exactly what Mike does on the tuning.http://www.tko22.com/parts.html
I am not a mechanical type, so I had Mike do the tuning. I am very pleased with the results. I also put my 3-9x50AO Centerpoint scope onto the Disco. It just barely fit even with high mounts. The 50mm objective is so large that I had to remove the rear barrel sight in order to mount the scope. That same scope would not hold-in on my .177 Crosman Phantom springer that has a pretty good kick. It does just fine on the "kickless" .22 Discovery PCP. After the tuning the trigger pull seems better; the breech seems smoother; and with the pressure in the gauge green zone, the POIs are the same at 20 yards for the four pellet types that I tried. This week I'll use a Caldwell Deadshot Fieldpod and see how it groups to 30+ yards.