Having an 11C that's had a ragtop put in, currently fitted with a supercharged 30hp, I guess I'm not a purist. Neither of these 'modifications' prevent the car being a 'good vintage VW' IMHO though.
To be honest, I'm not sure I am going to take my car to any shows this year, as I can't be bothered with the bitchy criticism that I get for it 'not being a real 11G.' I have spoken to a few other Split owners who feel exactly the same way with their cars as well, who don't take their cars to shows any longer because they can't be bothered with the criticism that they get. It's a shame really.
It's not just limited to the VW scene though. I only ever took my Mercedes 230SL to one Mercedes show. When someone sneered that it was wearing Avons, and not the 'correct' Michelin MXV-P tyres (at over £200 a pop), I realised that Mercedes shows weren't for me either...
I have my cars because I get pleasure out of tinkering with them and driving them. I don't build them to anyone else's taste but my own. Whatever my views are on cars - whether I like vintage, stock, slammed, resto-cal, or anything else, I don't feel I have any right to criticise what someone else has done to their car, and reduce their enjoyment of it.