Love to see the difference.
Do show pics please.
The t-piece is custom.
This was such a quick mod I don’t remember the details.
Seals really depends on what you get OOTB.
Most common way is to open the gearbox and then push the piston in and out by hand while covering the nozzle.
You want plenty of resistance pushing in and none the other way.
Then you add the t-piece and barrel and test again.
Barrel length depends partly on barrel ID/gel/hop up and what other changes you make to the piston/cylinder/gears. As it’s all nylon, you will more likely be improving the rps than fps. Nylon gears will only take so much before stripping.
I tried different barrel lengths but you can only get so much in a sub-200 blaster.
I also experimented with different springs till the motor and gears complained.
As is, the stock length is good and you do need a chrono. It’s not just for speed. Changes can affect consistency as well as speed and only a chrono will show it.
Gel inconsistency aside, a well-tuned unit can have only 2-3% speed variance while a poorly set up blaster can have a 20% spread.
Not only does that affect range, the interaction with the hop up will also vary and affect accuracy.
For me, the next change is a drum converstion.
I like to do 'what-if’s and 'why-not’s.