240 1987 240 manifold "down" pipe

Sprung leak in downpipe header. Made a buzzing exhaust sound underneath front seats and could smell at idle in winter. So, ordered the Starla header with fixed flange to cat. There was one large threaded hole for oxy sensor if needed. But, there were also two other smaller holes, threaded I believe. I thought they were for threaded hangers, but could not find any answers or parts like this after extensive search. Last night, before bringing to well referred exhaust shop, I looked underneath. There was not a flange at cat, but header was welded directly to cat.

So, shop did the same weld to cat today. But, they did not replace the rusted out bolt near 2 into 1 joint on header where there is a welded flat plate and bolt hole to anchor pipe. I can hear the whole exhaust rattling inside car. They told me there was a hollow sound from cat's interior going out. It's making bad sounds and I'd surmise is stressing on my upper manifold to head, without that achoring bolt on header plate. It also does sound hollow and pipe is knocking around below 1500 rpm. I also do have a lumpy cam installed, but this is way worse and annoying than before repair, at least on inside when driving. Does sound quieter without repaird leak on outside.

Shop said I can remove cat and go straight to rear muffler. I had IPD Sport exhaust installed 10 years ago, so removed the front muffler then. Still using the long exhaust pipe and muffler from 2 1/4" sport exhaust.

Were the two smaller holes on header for hangers to thread into? And, what bolt do I need for that welded plate on header? Also, will removing cat mess up engine computer? Was told I'd have better flow without cat. Thanks much for any answers to these ???'s

The smaller holes in the front pipe are test ports and you can just use bolts to block them off. The single inadequate bolt for the flat metal piece is an 8mm bolt. It attaches a hanger from the bell housing to the header pipe. Removing the cat just makes the car pollute more. The amount of performance difference isn't very much. It's better to have clean air than a catless system. What may have happened is the internal parts of the cat may be breaking loose and you may need a new one. BTW it's illegal for a shop to remove the cat in most states.

Personally, it's crappy work at an exhaust shop to not use the front flange to attach to the cat. But those shops don't want to spend the time to do the job right and welding is their goto solution for everything.

^^ It's illegal in all states to remove a catalytic converter long term. It's Federal, whether your state has testing or not. A shop can temporarily install a "test pipe" for the purpose of testing whether the cat is plugged.