I don’t know much about your car, but I’m pretty certain turbos would not be a cheap installation. I doubt headers / exhaust / intake would be any less than $1500 if done properly too…
If you want to be able to go fast from time to time, how about getting a nitrous kit installed? That’s probably the route I’d take with a luxury car with already ample power if I wanted to let it rip once in awhile in a straight line and surprise some folks…