16vs dont respond well to simple mods in terms of power, although an induction kit an exhaust will make it sound fantastic. Beyond this, most owners stick with a chip and de-cat - again, no major power, but they make it a little more driveable. Mods get expensive after this, though head work/cams/forced induction are the way to go for more power.
Most people tend to prefer the outside as standard too - who needs more than fat arches, bonnet bulge and wide bumpers? Ive just stuck back on some original Phase2 wheels too.
Theres no secret to maintaining the cars - just change the oil every 3-6,000 miles and get handy with the spanners (16vs are fairly maintenance intensive).