My shop did it for me (years ago). Got charged between 6-8 hours to install headers and swap diff (don't remember exact number). Exhaust completely dropped, and 1st time doing headers on an M5. Other than getting the springs on (mech said second person helpful, but not required), very straightforward. Oh, and that included time to make the SS pipe to mate to the stock cats actually work (he spent some time on that).I wanted to find out who has installed their own headers and the degree of difficulty.
My other question is if you had a a shop do the install how much did it cost to have it done?
Any and all info welcome.
Thread is seven years old (do not think that SS design has changed since then, however) and can be found here:As has been shared; rather straight forward.
The OEM exhaust is one piece as such it requires two in order to comfortably remove it.
Once out if using the OEM cats you will need to cut them at the "PROPER" place for the connecting pipes to fit well; and they fit very well if cut properly. Once cut “DO NOT” bench weld the pieces but rather install the headers; then the back half of the exhaust and then fit the connecting pipes into place last and then weld then with the assembly in place. The connecting pipe needs to be welded first around the inside tube at the cat after which the collar is slid into place and it too is welded creating the final seal. Once completed (if Tig welded) it will appear as OEM. Furthermore once the welding as described above is completed you will be done except for reinstalling the O2 sensors and misc. soft items under the gal.
Now as for removing the OEM exhaust manifolds;
The right side is NBD
However; removing the left side exhaust manifold requires removing the solo 16mm motor mount nut and then raise the left side of the motor about an inch; it is not rocket science here when up enough the manifold will slid right out. A word of caution; if you have a strut brace remove it in advance, disconnect the battery, and leave the hood open
Now once everything is out the installing of the 8 tubes can be awkward but not terrible. Once all 4 tubes on a given side are in place with the nuts snug but not tight we always slide the collector spring plate into place prior to final tightening so as to verify alignment of the tubes. Then prior to installing the collector we put some anti-seize on the tubes and within the collected and then with a piece of hardwood and a hammer simply tap it into place. Once in place the springs (likely because we have done so many are not a big deal). We have a couple bent tipped punches that fit into the slots and wholla…..
Hopefully this has helped a bit
The greatest thing I would say is “RELAX”, enjoy the process and even if you get to a point that you want to pull your hair out …don’t…..simply walk away for a few minutes and then re-approach the project knowing full well that “MANY” before you have completed it and that once completed she will breath so much better; to the tune of approximately 35 HP which you will feel from day one.