I have a 2007 1.3l rx8 4port and was trying to figure out why I had a tapping noise and loss of power and bad idle, so I unbolted the cat from the exhaust manafold and have a really loud knock/tapping noise coming out of the pipe does any one know what this is, or do i need a engine rebuild and if engine rebuild is Atkins rotary the way to go with a Bridgeport?

 

It’s likely the cat’s broken, you can sell it and put on a Midpipe if emission isn’t a thing.
A rotary specific compression will tell the health of the engine. That said, if the cat is broken, it’s a good time to check your ignition system, bad ignition kill cat.
if the engine is bad, send it to a builder. Don’t Bridgeport it, just don’t. Check thread “ported without a tune” where teamrx8 explains why not. Simply put, no port overlap.

 

Is the noise coming out of the engine? There's is really no good reason for that, you may want to pull the spark plugs and see what they tell you. Compression test if there is no obvious signs of damage.

A 2007 4-port? Where are you located? There is no such thing in North America.