I usualy use Bandoo timing belt costs around 300 to 500 Rs japanese and change every 40000 or 45000 KM. Why take risk :p.
I am not sure if the suzuki Mehran engine is Interference engine if thats the case than engine will continue to turn and cam shaft will not this will result in bent valves and you will end up getting ur head opened and getting it fixed for around 4 to 5000.
I remember my charade 85 had non interference engine and my mechanic use to say no tention belt chalna dey but recently bought ee90 and he straight away said 1st thing lets change the damn belt