There is a small hole already in that location. I saw a wee stream of bubbles coming out of there yesterday when I filled up, didn't take much notice, now this thread. So, I went out & had a look with the torch & yep, there it is, small air hole.
What I also noticed was grit in the tank!
Tank itself is fine so must be from the petrol! Why can't they filter it at the pump & clean those out instead of pumping the crud into our tanks & we have to change the filter cause of their 'dirty' fuel!!
Anyway, looks like I'll be cleaning the filters this summer, do I need a new gasket or is it a rubber re-useable thing? I'd do the external HP filter mod as well, but I've got wiring & relays all over the place there & can't be arsed moving all that lot as well. It's not blocked at all, had a nice wee full throttle burst a couple of times yesterday & no complaints from her at all - or me!