i bought a rx8 about a month ago and I have a knocking noise that sounds like a alternator belt coming from the engine and the car now is a bit more sluggish starting cold would this be a coil pack and plug job or something else exhaust seem to be Lourder aswel noise goes when rev up to

 

Well if it's knocking then find the knock. Sluggish start could be a bad battery, bad starter, or both.

Did you get a compression test on the engine before you bought it? If not then made a horrible decision.

 

Been starting fine till today
knocking is at front of the engine doesn't seem down on power

I didnt do a test but the price I got it for i didn't mind if I had to put a refurb engine in

 

Should say aswel it's gone worse since it was flooded due to garage not warming the car up when I took it to them

 

It didn't flood because they didn't warm it up.
It flooded because of another underlying issue.
Usually bad ignition components, weak battery or starter, and bad compression.
A healthy engine won't flood even if you start it and shut it off.

 

My 2004 was running choppy, had knocking and even a howling sound up front. Didnt seem underpowered but Idle was way down and sometimes would stall at stoplights. Starting often seemed sluggish and like a low voltage situation. This may not be your issue but I grabbed my stethoscope and went to listening to everything under the hood.

Turned out the previous owner had apparently not properly tightened the idler pulley after replacing the a/c belt. This cause excessive vibration and the belt to pull the pulley at a slight angle.
When I pulled off the pulley it barely would move and actually got stuck unspinable while I was messing with it in my hand. Put in the new pulley and the engine runs very good now and much quieter. Starts much easier as well!

(P.S.) Also recently had an a/c compressor go bad on a different vehicle which nearly ruined many parts when it seized with the engine running... Definitely look around well. A few dollars prevention certainly goes a long way on these cars...

 

Thank you I'll look when I get a day off