vitz fuel pump: (latest prices) Saddar Rwp
RS 1k (china)
RS 2-3k (Thai)
RS 4-6k (Toyota Orignal) not 3s dealership rate
all three in Saddar
the stutter sound u mentioned chuu chuu is NORMAL .. its an indication that ur fuel pump is working FINE!! .. fuel pump will start to weary only if ur SELF takes longer than HALF SELF to start the engine .. i.e. longer self's ... and keep in mind ORIGINAL fuel pump that came with the car, is meant to last WITH THE CAR ... only fuel FILTER might need a change (that too not necessarily) ..
just get ur Cat Converter removed / serviced from TOYOTA ... and u'll b fine.. and use Fuel INJECTOR Cleaners for bettering performance and achieving good milage...