F355 2.7 engine/exhaust noise

I am currently restoring a F355 2.7 which needs a major done where i will DIY most of the maintenance needed with time as this is one of several project cars i have.

However i have a noise or rattle problem and I have tried to source where it comes from and would be glad if someone could give a guess from the video below.

Early suggestion would be that the muffler is bad and probably the cats(already replaced by former owner, some cheap Ebay ones, EEC).

I have no white smoke coming out from the pipes so i guess it can't be the exhaust valves, however i do get a solid slow-down 1-4 that comes and goes when the engine is idling and up to temp, however the RH cat doesn't seem overheat from the look at it so it can be a faulty temp ECU or probe, need to diagnos that more when i get time....

 

Thanks, i will remove the cats and inspect them and replace with test pipes first, i get a slow-down light from the RH cat so it could be a damaged clogged cat.

I hate it when some owners gets cheap on these cars and buy the cheapest crap they can find just to buy time.....i found out the cats replaced by previous owner cost about $150/pair EEC FA6002T on Ebay.

 

I have solved the problem now, i replaced the exhaust system from Nouvalari and replaced all hardware like donuts etc, however i kept the original headers as they are fine.

The noise is totally gone now and it sounds as it should be.