Should i buy this car or save my money?

I am 18 years old, have been working full time for the past 5 months or so, and have been able to save up 4500 bucks over the past 2 years. i currently drive a 1999 monte carlo. its been a great car i paid 1200 for it and its a southern car so not alot of rust. i have barely put any money into it at all over the past 30000 miles. the only problem is i love acceleration and a sporty car. i just called this morning on a 2000 pontiac grand prix gtp. its the supercharged one and its really cool looking, has a custom hood and looks really clean. but yet my car is really clean too. im in a tough spot because my car has been so relaible but its just not that fun or maybe in this economy i should just be happy and keep saving up for the future even if i drive a 160hp car that i still love anyways. just seeing what others think. i will have to pay premium gas is i get the grand prix i guess that will kinda stink after a while. also i almost forgot i have a great parts car for the monte carlo with a really good engine and trans in case mine blows up