bung,
Here's a link to a recent thread on the subject which has a link to videos on the britironrebel site. One of them shows the removal of the restrictor plate which has a very small aperture for the inlet air to squeeze through:
restrictor plate thread
I removed mine from the Scramblers airbox at the outset when I modified my exhausts and re-jetted to suit in one go, changing the pilots to 42 and putting in Thruxton needles with a couple of shims. That was based on tips from this site and from Peter Jenks at Jenksbolts. I've changed the mains four times now 115 to 122 to 130 to 122 then back to 130 when I opened the intake plate right out like you did. The bike ran stronger on the 130's than 122's with the opened out plate. These are butt-dyno figures, I haven't been to a real dyno yet, but I run my bike to the limiter in 2nd then fast as it'll go in 3rd on the local bypass to see how well she's going. I suspect I'm on the rich side of right, but the bike runs the strongest with the jeting I now have.
