1993 YZ80 Two Question

I recently got a 1993 YZ80, and put blue rims on it and a FMF Shorty silencer. The stock pipe has a huge dent in the back of it where its not visible. But my friend has the same bike and his is the same year, and his doesn't have the dent and his has a lot more power. Mine also doesn't have the same sound his does. Mine doesn't have that clear ping ping sound that my friends does. It still sounds like a two stroke of course, but it isn't as loud or as clear sounding as my friends. Mine just sounds to be bogged or something.

1st question: Is the dent the reason for power loss on my bike?
2nd question: Would a FMF fatty, or Pro circuit platinum pipe be a good investment? People have told me not to mix and match so would it be best for me to go with the FMF fatty?

Thanks for the advice and I just had a fresh top end put in a few weeks ago so it can't be that. It was doing the same thing before I got the new top end put in. It probably needs jetting. If I get the pipe for it, I will just take it to get it jetted, since everyone says if you change the exhaust you should get it jetted. Thanks for the kind words on the bike .