Tuning Fx 177 barrel liners

I've tried to figure out if they make the superior liner for 177. So far I've gotten mixed results, my local FX dealer says that FX doesn't make the superior liner for 177. I did find a dealer that sells the superior liner in 177 (website stated so) and bought it, but didn't see any improvement from the regular stx barrel. Inpecting the two liners, they look the same, shoot the same, can't find any difference. 

Does anyone have knowledge about what is true or not. 
 
FX has a new machine just for producing .177 liners, this is due to come online imminently as I understand it, I have tested a couple of liners made already including the 600mm .177 and I must say they are impressive!

Do you know if they are going to make a Superior Heavy for .177? I have a weak spot for .177 slugs, and they are AWESOME, when you can find a barrel that likes them. I had to machine an Alfa Precision barrel to fit my Maverick for .177 slug duty. A 700mm FX barrel sure would be sweet though!