I was recently rear-ended and the Y-Pipe loosened up from the Mid-Pipe. After tightening it up, the juncture is still leaking. I attempted to get the gasket dimensions from the manufacturer (Megan Racing) but they have not provided a response. Would anyone here happen to know what size gasket I need? I know that the flange is 3" but need to know the hole diameter.

 

This should be the part you need
https://www.amazon.com/Berk-350Z-Y-P.../dp/B008HRX8JI
Also you might be able to just get by w/ Permatex Red high temp RTV sealant if it's a small leak. Apply it to both sides of the gasket, just lightly snug down the bolts, wait an hour then torque to spec.

 

Awesome, I was considering that one the other day but wanted to be sure (since my Y-Pipe is from another manufacturer). Just as a safeguard, I went ahead and ordered a 2.75" and 2.5" One of those will definitely work. Thanks for your insight!