So, I'm usually the first one to bitch about the quality of parts, but I actually have a positive experience to share.  I was recently working on a Pontiac 8 cylinder engine with a significant rear main seal leak.  Most of the Pontiac sites say "just live with it" but this was a really aggressive leak so I waded in.  When I took it apart the 2 year old Felpro seal had disintegrated so that only two 1" pieces remained.  Turns out the Felpro seals no longer have asbestos and tend to dissolve.  I got in touch with Butler performance in the US and he sent me a new 2 piece rear main and a one piece pan gasket.  His stuff is top quality, installed quickly without having to pull the engine or drop the crank and it sealed up 100% the first time.  As a side not, this rear main was so bad it was creating a vacuum leak through the PCV system so it actually runs better now as well.  Worth every penny and Butlers does not mind helping out with technical help.