A 20 as said is pretty tough if it's reasonable condition to start with, they can be a bit flat but don't mind revs so use them, as Roy is saying they can go ok on a track if the car is setup & driven well. If it blew which won't happen easily I'd go a 25
If I was to do it over again I'd just do the dose pipe, none of that other frilly stuff.
I live my life a dose at a time, for those few seconds or less, I'm free.
Is late series 2, most places that have the gaskets should have the grommets, otherwise the local dealer will probably have them, or replace the screws with bolts same as the neo setup
I'd go for the Turbosmart, it's easy to get the springs if you want to change them later & although nothing really goes wrong with them you can get diaphragms etc. Tried & proven.
Otherwise the Kando.