You can get into a 924 turbo for around 2 grand. They come stock pushing 7psi, but you can turn the boost WAY up and make twice the stock power with nothing but a boost controller. Add an IC, some fuel and spark and those cars will push 300hp easily.
300HP Porsche for about 3k total. Seems like a fun track beater to me. Sure it's a low-end Porsche but it was still made in Stuttgart and it still corners like a slot car, The FC3S was called a 924/944 knock-off when it arrived. And it was.
/end Porsche fanboy mode.