Originally Posted by pnwR53S

Having received two sets of the Milltek cat back with the same flange on the long main pipe segment have the same off-square made me suspicious. I got up at 2:30 AM to call Milltek in UK. The person the phone said he is not technical and asked that I get a photo of the ID tag of the part in question, and he will relay the issue to the right person. The ID tag is the small welded on stainless steel plate with part markings. Every piece of the Milltek kit has a unique ID tag with "Made in England" etched on it.

I went back to bed after making sure Leigh has everything he need to follow up. By the morning Leigh has reply with the answer with an email. It as sent within a few hours of our last correspondence. I was impressed with their responsiveness.

He had checked with their production team who checked their master pattern, and the off-square angle of the flange is apparently normal, which I interpret it is as per designed.

The next day I decided to go ahead and give the installation a try to see if everything "square up". My original hangup was the ~7 degree of offset angle will skew the main pipe to one side instead of well center in the exhaust tunnel, and possible push the O2 sensor against the aluminum heat shield.

It turned out the ~7 degree offset is mainly vertical component, with no measurable horizontal component. Being only vertical component it is absorbed by the stock header's flex joint. I was able to reuse the stock gasket that consist of a ~1mm thick stainless steel sheet metal. When all the joints (there are 3 in total) are properly tightened the long main pipe sits perfectly center in the exhaust tonnel. It is also horizontally true as well as long as all the exhaust shock-mount hangers are in good condition.

My other hangup on the Milltek's hanger bars lacking the nubs turned out to be immaterial, as least with my specific unit. Once the three joints are properly tightened the muffler assembly is rock solid with respect to the Mini undercarriage. If I grab onto the tail pipes with my hands I cannot wiggle them in any direction due to the excellent (6 point support) hanger systems of our Mini.

I suspect Milltek chose to not adhere to the interface boundary (maintain a perpendicular plane of the flange) of the stock header was done to accommodate their own header, for whatever reason. To this accept as the cause of my original concern. Now seeing the installation result I am satisfy that it is an excellent product I retract my charge of shoddy workmanship.

I chose the Milltek over other competitions because of the one-piece muffler assembly design, country of origin, and price. Seeing how driving on track can beat up an exhaust system I did not want the Borla that has too many joints. The Stratmosphere appears to be very high quality, and most alike the Milltek and with the nubs on the hanger bars. It is however priced much higher. In all I am now quite pleased with my purchase.

Originally Posted by gumbedamit

I'm glad everything worked out. Do you have pictures of the joint connected to the CAT?

Originally Posted by Zsm

That's great news on the outcome. Let us hear what the new exhaust sounds like once you've properly broken it in.

Originally Posted by ECSTuning

That's good news! The exhaust, when broken in, should sound very good.