My car would not cross 120 km. What is the problem? What is maximum speed of the 2004 Octavia 1.9 TDI engine superup
There are a number of versions of the 2004 1.9 TDI engine which develop between 90bhp and 150bhp. That said, even the 90bhp version ought to be capable of 160kph plus.
The first thing I would do is plug the car into a fault code reader. I'd scan it with a tool such as VDCS (the Lite freeware version will be sufficient for your needs here) and look for any fault codes. If fault codes exist they will point to a problem which can be addressed. If no fault codes exist I'd next be checking the security of all pipework under the bonnet.
If the car has not been serviced recently, I'd give it a full service as this may simply resolve the issue with no further work. If work has been done on the car recently (i.e. timing belt, N75 valve, etc...) I'd check that has been done correctly and the fault may have been introduced due to an incorrectly implemented repair.