How to repair my Honda cb twister exhaust system?

Honda twister 2010 bought.

i was having problems in power delivery in my bike
After a lot of research i'm 100% sure that some blockage or some fault in my exhaust system is causing it. As back pressure is more so scavenging is not done properly.

when i showed it in an authorized service center they told me to put a new exhaust.(costs Rs 4500/-)

i wanted to know is there any way to repair or clean my bike exhaust or any other way? Do i have to put a new one?
and what are the future effects on the bike engine due to this problem?

Hi the exhaust is not likely to be the problem what is more likely is when it was new if it was not run in properly some one wrecked it. By being brutal with the running in and now the engine is useless.