E28 Exhaust replacement questions

["Doss Donaho" <ddonaho@xxxxxx>]

I have decided to replace my cat, resonator, and muffler with SS replacements
from Stebro.
The parts are supposed to bolt right in and come with all the flanges, clamps,
etc I need.
I was wondering if there are any parts of the hangers that I should replace
while I'm doiing the work.
It seems logical to replace any rubber "donuts" and such but since the car is
having body damage repaired I can not get under it to see exactly what I
need.
Anbody have any helpful hints?

I am also contemplating removing the exhaust manifold, porting,
extrude-honing, and ceramic coating it.
Removal and instalation seem simple enough.  I will definately port it and
ceramic coat it if I remove it.
Do any of you have an opinion on the extrude-honing process and what I should
expect from it.  If any of you have done it before, would you do it again?
I am wondering the effectiveness of this process on cast iron.  Specifically,
how smooth can it get the passages and will smooth passages help or hinder the
flow of gases?

My goals are to improve the exhaust flow (in anticipation of other engine mods
this summer), reduce underhood temperatures, and install an exhaust that will
last as long as possible.  The car is a 86 535i with 65,000 1 mile trips on
the odometer.  I have already decided to keep it emmisions legal, which is
part of why I'm not installing a header and why I am paying $700 for a new
cat.

Thanks for any thoughts or advise you might have.
Doss
86 535i

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