i did an LS swap into my 93 hatch, using DC 4-2-1 two piece header, it didn't come with the adapter or gasket (the O-ring) that was suppose to connect to the cat (some cat from integra). I bolt the exhaust system back together, and there seems to be a gap causing a leaking exhaust. What kind of adpater or seal can solve this? or should i get an after market cat to replace the integra cat in order to make header and piping fit perfect?

 

you can re-use the donut gasket off your old exhaust manifold,assuming the header has the stock size collector.
Chris

 

i tried that too. the doughnut off my D15 header was too small.

 

one off of a b-series will work like an integra they are all the same except the jdm type r