Best to start a new thread with your question rather than resurrect a 5yr old thread. But to answer your question. No you do not HAVE to get a new pipe with your carb. But you definitely CAN get a new pipe. Dont go crazy. I advise as others up top have and get a circuit pipe. You will notice a difference right away.
And if you have a za50 engine. Please take the time to read up on some of the immediate maintenance that is needed on those engines. You can find lots of info on the wiki. Just get to the puch section and find za50.
We are all here to help. Ask a question. Just make it your own after doing some leg work. Or else roffman wont be gentle, but he is one of few who knows most about za50 around these parts.