Interesting thoughts on tuning in the previous few threads. For a modern springer the one thing that annoys me if I own the rifle is 'boing'. My 77k boinged when new all those years ago so I cleaned it up, added beer can spring sleeve and hey presto, no more boing. Later I added a delrin guide and after that a top hat; both home made. As hinted above, I do not think a 'prefessional tune' would give me a sweeter, more accurate rifle but I accept that many people do not have the aptitude or facilities to work on their rifles other than to add a 'tuning kit'.
For older rifles, my attitude changes somewhat. For something like an Airsporter or Mercury I will clean it up and maybe add a piston sleeve if it boings but other parts remain as original. For older rifles e.g. early Diana 27, they get a clean but nothing added. For these latter rifles the 'firing experience' is all part of the package.
Cheers, Phil