I was going to go see about a muffler for my 81 rx7 tomorrow. I have never messed with a rx7 exhaust system and was just wanting to hear from you guys about what I should do. What size inlet would I need? Any recomendations for a reasonable priced good sounding muffler?

I dont want a ricer sounding muffler. Just something to give it a deeper tone with out making it sound annoying. Im also not looking to spend alot of money, just figured if I could change the exhaust note fairly "cheap" I would go ahead and do it. Any help would be appreciated.