I'm confused here... You seem to have a budget of somewhere around $35,000-40,000 based on your dad offering to buy you a boxter or a new z28... Basically sounds like money is no object.

You want to achieve a 9 second quarter by the time you're 21.

Are you wanting this to be the same car??? Why not just get the nice new z28 your dad is offering. The new Z28's are very nice reliable cars that will do 13's off the showroom floor, 12's with a few basic mods and will definitely own the streets over the riceboys.....

Then for just pure speed- spend a little bit of $$ and buy an old nova or something, gut it and build yourself a strip only car to achieve the 9's. A 9second car will not exactly be very streetable or comfortable... but can be very fun to build one and keep tweaking it until you get the speed out of it you want.

Sounds to me like you have the $$ to do both... have a fast comfortable driver, and a fun hotrod buildup.