I think you could probably drop the attitude. $575-$600 a week still isnt enough to have a car that you want to enter into 'shows' as you said. I dont want to bring a harsh reality to all this, but our cars cost alot of money to repay and maintain, especially if your a young tacker. I wish I had been 'enlightened' before i took a big ass loan out and bought my car, I had a NA S13 which was ok, payments were managable and nothing ever went wrong on it, I wish I had of kept that for a while longer before I got the R33
Everyone on heres trying to give a bit of advice because id say 95% of people were in a similar situation and are trying to help you make the same mistake. Before you have a car you think all you have to do is pay off the loan, so $600 a week is plenty, you didnt mention if this is before or after tax btw which makes a big difference, but then you start paying insurance, petrol, servicing, tyres, repairs, upgrades, etc..
I'd hate to rehash on what other people have said but at your age insurance on a 'decent' car, it'll be at least $3000 a year. I cant be bother writing anymore because it seems as though you didnt read any of the previous posts, so I doubt your going to read this one...