Installing an R53 Mini Cooper Header
I had read on the forums that as the factory exhaust manifolds aged they had a tendency to develop cracks, and this was a good enough reason for me since I wanted a header anyway. I found a GREAT deal on a slightly used (few weeks) SuperSprint Header and new high performance metallic cat and that clinched it- out with the old exhaust manifold and restrictive pre-cat/cat and in with the new SuperSprint header and performance cat.
Standard Disclaimer: ANY USE OF THIS INFORMATION BY YOU IS AT YOUR OWN RISK.
I used Randy’s DIY guide HERE to get a feel for what was required and involved.
Since I was also removing the OE exhaust and installing a new system, I raised the car up at all four corners using four jack stands. You only need to really raise the front with a header only installation.
The exhaust is disconnected from the exhaust manifold/catalytic convertor assembly using a 15mm wrench. I have read that some Mini Coopers do not have the same pressed-in stud and nut setup I had so you may need to adapt this step to fit your specific scenario. Now is also a good time to remove the post-cat O2 sensor using a 22mm wrench. Looking above the pre-cat you will see the pre-cat O2 sensor, also removed with a 22mm wrench- this one is a little tougher to access, you just have to figure out the angle of attack and it may be easier to do with the driver side heat shield removed.
I went ahead and removed the driver side heat shield, two speed nuts removed with a 10mm wrench and two screws removed with 8mm socket wrench. Removing this heat shield not only allows easier access to the top/pre-cat O2 sensor but is a MUST for getting the exhaust manifold out of the car.
Back up top, there is a heat shield that needs to be removed- two bolts removed using a 13mm wrench and it helps to bend the rear heat shield up and out of the way:
Now you can see the OE exhaust manifold and the eight bolts you will need to remove requiring a 10mm socket wrench- a narrow headed wrench is much easier to use because space is tight:
The exhaust manifold can be carefully lowered until you get to a stopping point- I also moved the upper O2 sensor out of the way before lowering and carefully placed it to the side:
Getting the exhaust manifold out around the front sway bar is a little tight but doable, the trick is to push it as far to the right as possible while hooking the left side over and around the sway bar- you may need to use a little force since it is tight between the sway bar and body of the car:
Comparing the OE exhaust manifold to the new header, it is obvious to see where there was room for improvement:
I cleaned the head mounting surface and used a new OE Mini exhaust manifold gasket before bolting down the new header. I used an alternating pattern to tighten bolts starting with the center bolts and working out on each side. The torque spec is in the TIS document linked at the beginning of this write-up:
I had to modify the heat shield, some have cut theirs but I removed the rivets and bent it into a more header friendly shape after bolting back in. I made sure there was plenty of room for vibration/movement without possible contact so no rattles:
Don’t forget to bend the rear heat shield back down:
I had to adjust (bend) the heat shield above the power steering pump slightly so that it did not contact the header. Some of the other heat shields may need massaging as well:
The upper/pre-cat O2 sensor was installed:
Next the performance metallic cat was installed- the donut gasket and then the cat and post-cat O2 sensor:
Finally the exhaust can be connected using a new OE Mini cat gasket or a thicker cat gasket with a larger inside diameter. I could not find one that was perfect but did find one that was close- I made it perfect (a little larger ID) by placing it on the exhaust mid-pipe flange and using a ball peen hammer around the inside hole to cut away the excess before installing. I had some bolts in my “mystery box” that were from an old car exhaust that worked perfect here, I have read M10x35 should work:
Enjoy a little more sound and power…………..