BSA supersport Transfer port modifocations

[evert]

Many years ago, I shot a tuned .25 XL lightning that went "thokk" when fired.
It had a V-Mach kit and the transfer port restrictor removed (no power limits here in norway).

I've been happy with my own Lightnings/Supersports so far, using the Titan #1 on tight delrin guides, but they seem a bit bouncy and dont have the same "thokk" but more of a muted "thudd" when firing. As they have 29mm pistons I've not thought much about it as large diameter pistons probably bounce more than small diameter pistons.

Thinking about the transfer port, removal of the restrictor screw on the gun I shot meany years ago probably meant that gun had a 4mm port? The original ports on these (At least the Norwegian full power guns that came with the heavy piston weight) measure about 3,2x10mm, which means the may benefit from opening up?