Defintely snag the exhaust manifold (and intake manifold) if you can.
Turn in your EGR exhaust manifold (and intake manifold) for the core charge(s).
The non-EGR exhaust manifold will flow better than your stock EGR exhaust manifold.
There is less turbulence without the the EGR port.

You can pass on the ceramic coating if you are not after any additional performance gains on top of those acheived by installing the non-EGR exhaust manifold.
With ceramic coating you get slightly better turbo performance due to higher velocity of exhaust gases...and the bonus of lower under hood temperatures.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022