Hi first time poster here. I awoke my sleeping bird about a month ago after it being broke down for about 10 years. Its been a LONG time and I seem to have more questions than I know what to do with sooo I thank you all in advance for your help.

first of all let me just say that horsepower to me takes a back seat to engine efficiency. Im thinking about putting a free flow cat and muffler on my 91 firebird 305 tbi. Here are my questions.

1. Will a free flow cat and muffler throw off my fuel table? (economy)
2. Will the computer start throwing codes due to a new exhaust ratio?
3. IF I disconnect the battery to reset the computer, will it adust itself to the new exhaust flow?
4. What brands do you recommend if at all. A catback is out of the question. Im using stock pipe and just replacing the cat and muffler thats it. Ok guys .. feel free.. fire away!

ps. I dont want it to be so loud I cant hear myself think. I need a nice mellow rumble.
Its a single pipe design with a single cat and muffler.

Just throw the cat/muffler on. You will be fine. No need to do any of that. There is a whole catback/muffler thread stickied at the top of the page.

if your going to replace the cat and the muffler, why not buy a catback and a new cat. converter...cuz most places will have to cut yours off, then reweld new pipe up there anyways to make it all meet up.

exhaust work isnt cheap, and cat backs really arent expensive depending on the name...

magnaflow is a good, and fairly cheaper catback system/ or just muffler.

i dont recommend flowmaster...but some people will.