I have a UTG drooper mount, low Simmons rings and a Hawk Vantage 4X12. It's all pretty good quality, but the problem with the drooper mounts is they are too high. By the time you get rings and scope on the whole thing is too high for a good cheek weld. You might check BKL technologies, they probably have a better solution but it will be more expensive.
Ghetto tune
Is using a 2 litre soda bottle as a "delrin sleeve" which it isnt.
Cut off the top and bottom off a 2 litre soda bottle (I used green) to get to the middle flat work stock in between.
If you know how these airguns work you might be starting to see where this is going.
The sleeve goes in the piston to cusion the spring from rattling around while cocking or firing. I used a semi heavy coat of dielectric grease on the spring to act as a dampener for it. The soda bottle needs to be cut pretty exact in size, which isn't hard to figure out. If you mess it up you have more material or know where to get it. You want it the right length which is easy. The width is trial and error, cut a little at a time so when it fits inside tge piston the ends just meet. It will be a tube like a paper towel roll but with a cut lengthwise to make a perfect circle and fit in the piston.
If you try this, Be Careful. Wear eye protection. When you take the gun apart it's still under spring tension, but nothing like when it's cocked.
There are a whole bunch of videos online about taking these apart.
I did it with no help and pushing the gun against my work bench. The problem with that is you really need three or four hands. If I was to do this on a regular basis I'd build some kind of spring compressor.
All this to not spend the money on a Vortek tune kit. I just wanted to see if and how it would work. It works really good actually. The gun is much nicer to cock and shoot, super smooth.
If you go the Vortek route, you still have take the gun apart just the same, or send it off.
I helped a buddy install the Vortek kit a few months ago, its nice and he picked up some FPS.
ETA: nope I was wrong, the sleeve has to have a gap for the action.