You might be refering to me about who switched the hop-up unit entirely. I started a review over at ASR and the internals to that gun have beena nightmare for me.
Ive never been able to get a KA gearbox to work with a KA hop-up unit, so I switched for a star,CA, and G&P. it yeilded better FPS gains than the stock one at about 330fps but the spring was rated for over 400. I too had my Guarder cylinder kit installed even though the stock compression seemed great.
My solution ended up that I had to put a whole different gearbox into the KA externals with a different brand hop-up un
