Well this is again a very difficult question. There are so many views about this thing.
After few discussions I came to the conclusion that this converter needs to be maintained very well. The fuel in Pakistan and the environment makes it in bad condition very fast. Due to accumulation of various carbon containing compounds it makes the breathing of engine difficult. This causes drag on engine. More bad the catalytic converter will go, further bad will become the drag on engine. And this may lead to serious damage to engine.
Many pakwheelers suggest to clean the converter with various tactics. You can search the threads. One pakwheeler said that one can clean the converter by putting muffler in hot water and slowly pass water through it.
The catalytic converter removal changes the sound of vitz. The sound increases. Plus the emissions from the engine become further bad for atmosphere.
I thought alot and in the end I concluded that I must get rid of it as I do not have much time to spend cleaning it. It is tough to remove whole muffler every few thousand Kms and clean the converter. And it is also tough to conclude that the converter will really get cleaned. and who will tell that the converter needs cleaning when we cannot see it?
So, I chose to simply remove it and get myself rid of all bla bla bla.
Now noise has been changed but i am happy that I do not need to think about the drag and stuff.
thats all. If you want to keep it it's your choice. Many rides in the world work with these converters and they are doing fine. Here I do not know why hum bohat jald dar jatay hain Anyways please do search other threads extensively before comming to any decision. and do update me what you have decided and why.