ok guys here is the low down on racing your z.
I raced my car in 2B Marquesorts for about 4 yrs in the Vic state series. The car was pretty competetive for the first few years but is definatly outclassed now because you are not alowed turbo's and the l28 is as far as you can go. In 2002 I finished 5th outright but the car would be lucky to finish in the top 10. My car (before it got crashed into.which i am currently rebuiling) has l28 taken out to about 2.9l with a very modified p90 head runing triple 45 webbers on AVGAS. It is putting out about 250-280hp. It has fibreglass front quaters, bonnet, hatch. full roll cage and all the hevey bits pulled out. 16x10 wheels with slick tyres r200lsd big brakes etc etc other works really modified.
You could build I nice spaceframe z with big turbo rb26 and lots of other cool bits and run it as a 2A invited sportscar but it would cost a packet to build.
It gets quite expensive to curcuit race your car as the entry to the state series is about $290 for the two days and then you have fuel and all the running costs (and also the risk of some dickhead running into you!)
Having said that theres nothing more fun than getting out on the track and beating a porsche!!!!!
There is also sprint meetings that are a bit cheaper and you dont need a full cams licence but you dont get to race others on the track it is more of a time trial.
Anyway if you have any other questions I would be more than happy to chat.
Ash