I've got a 94 200sx that we use for track days and its been great.
As standard they are very very average but once the suspension has been improved they are quite good fun.
Definitely not as tuenable as a Cosworth, if you want big bhp it'll cost a lot and then you'll have to modify lots of other things as the standard car is not designed to cope.
The S13 models (1.8) suffer badly with worn bottom ends and rust and have sloppy suspension and poor brakes. The S14 is the one to go for if you can.
The best thing about them is jap reliability.
Our one has been mildly tuned, has very little lag, big brakes, lowered stiffened suspension, decat exhaust, Yokohama A048 tyres, harnesses etc and is very very good on the track. Eg at Bedford and Donnington was quicker than a lot of very quick cars. Surprisingly neutral for a rwd car as well.[img][/img]