????????????? yes there is a "donut" gasket that goes in between the y-pipe flange and the flange for the cat...or in your case the straight pipe.....when you say the word "thingy" it brings other thoughts to mind 
"Youth ages, immaturity is outgrown, ignorance can be educated, and drunkenness sobered, but STUPID lasts forever."-Aristophanes.
--93 pgt,headers,intake,borla=14.9 1/4mile
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