I may have missed the point on both of these types of day but I'm really not sure i "get" it?
Under 25s - what possible difference does the age of the driver make? Surely it's track experience rather than age that should group drivers? Plenty of 23 year olds will be very experienced track drivers while plenty of 40 year olds wont be. I did my first TD at Cadwell when I was about 22 and there were nutters like david Yu flying around in his 700bhp GTR, all part of the fun....
Unmodified cars. I understand that some people might prefer to do a TD this way if they are novices but I really think you're limiting your market to people who aren't going to do very many. As Harry says, part of the fun of a TD is the variety of machinery and anyone who gets the bug will do a few mods to their car - brakes for example (esp if they have bmw M

) and be immediately excluded. Plus of course, seeing the mods that people make is inspirational.
Finally, will you be offering (maybe you already do) TDs where stock cars aren't allowed? Otherwise all this does is limit the MSV days available to anyone with a modded car.
Sorry if that sounded like a rant, believe me it wasn't, just think it's a bit odd
