Aftermarket Pipe Leaks around Exhaust Donut

[Just-Tri-It]

The aftermarket pipe (one on the right) on my 85 Z has a large mouth on it so that even with a exhaust donut with cork and metal it still leaks somewhat . I notice there was suppose to be a separate round piece for the Z exhaust that might make the exhaust jug bigger and fit the pipe if I can find one. Or maybe someone has the same pipe and can tell how you got it to fit tightly at the jug. I don't believe it's a DG pipe but I can't remember the name. I have a DG and the mouth on this one is larger than the DG.
And does anyone know if this muffler is still made. Part of the name is gone and the inside of the pipe is in pieces. Thanks
107446107445

[MTS]

Not sure on the silencer, But i had similar problems with the DG on my tri-z Flange was WAY to big...Had a proper sized flange welded on by a local pipe builder...think it cost me 30$...and some high temp Rtv.....Good to go!