For the popping, I suggest checking the header nuts to make sure they are snug. It’s a common issue for those to loosen over time. If you remove the header, it is highly recommended to have new gaskets before reinstalling. There is a tightening sequence to those nuts as well. You should follow that sequence and torque specs specified in the service manual. Someone here should be able to provide a link to a service manual for your year. BUT, you should do a search on this site first then post a new thread asking for a link if the search comes up empty. Finally, someone smarter than me will most likely chime in and let you know what the brass nozzle thing is. You’ll probably get more tips and info on your popping issue as well. Welcome to the mad house.
Did it ever have an aftermarket exhaust?
Sent from my iPhone using Tapatalk