bro rayson, frm my personal experience driving a lousy car (last time drive a 1996 model nissan march) i try to pump 2psi above spec to improve FC (fc for old car very bad, ard 10km/l although 1.0L engine) and it was very scary. my car would skid when roads are wet. not too fast. 50kph and a little more brake pressure enough to skid liao. but once i reduce the pressure back to recommended, the skidding reduced. i was using falken tyres. 155/70 R13. small tyres i know, but the theory is the same. if you are safety conscious the little drop in FC is worth it. for the latio i only pump 10kpa above spec (240 front/220 rear).