I have the 382,00 credit RUF CTR2, and I really like it. I'm not sure if there's a race you need it in though. I use it for all of the Rally Races.
I have a RUF 3400S(or whatever it's called), but I haven't done anything to it. But it's a great little car stock in my opinion...
I have a stage 3 turbo on mine, but I'm not sure if you can put one on the 160,000 credit RUF.