Well its most likely not a real Sylvia, probably a 240SX (Sylvia is the Japanese version of the car). They can be pretty quick, but like anything it all comes down to whats done to it.
As for racing him? I'd say screw it, especially if he races like an idiot. Tell him to go to the strip if you want a clean race. That way he cant play dirty without some serious repercussions.
Jeff you know that guy inour town with fake Sylvia , that was ex 240SX and he bought bunch of parts from Japan to make Sylvia , now is right hand drive , built 20 something engine (SR20 don't remember) , it pushing 320HP with tons of boost
All show and he never go
i pretty much do the same as Robin. I let them think their car is fast and let them talk. Just keep in the back of your mind that one day he will be racing on the street and get caught or wreck or blow his car up. one day that WILL happen to him. if he calls you names and talks crap about your car, just get him a diet coke and some wheat thins and then sucker punch him in the ovaries and run like hell, girls like that can't catch up to you. or just tell him you don't care what he thinks and that you have better things to do than prove anything to him.
Have him take you for a ride... Someone who talks this much smack would have no problem showing off for ya. Then you can gauge how full of crap he is, or if he's tellin the truth.