Is there a gasket between the O2 and the down pipe? I don't remember one being there... But when I pulled it off, it looks like someone rigged a gasket and put it in there.

 

It doesn't use a gasket especially a Donut style gasket. Some people run it without a gasket and some with permatex copper gasket maker.

However when I was using their downpip I would use an RX-8 downpipe-cat gasket and it sealed perfectly. Its basically an O style copper gasket that crushes slightly for a tight seal. Its also 2.5" inner diameter, perfect fit for what we need. Most BR downpipes I've seen after removal have black carbon leak marks , but with this gasket my flange was brand new perfect clean with no signs of leaks.

Just so you know what it looks like.



You can buy them either online at some places, ebay or from mazda dealership.

http://atkinsrotary.com/store/catalo...t-p-17381.html
http://cgi.ebay.com/ebaymotors/Mazda...Q5fAccessories

 

+1 It doesn't use a gasket. I checked with their shop and said no gasket, however I have to agree with BluEVOIX on the leaking issue. Just removed my buschur downpipe to install an O2 bung for my wideband and saw little black carbon marks on the lip of the downpipe meaning it was leaking, but not that bad. I would use a copper gasket to make sure it won't leak.