It has been discussed on many forums for several years and all experts agree that you should remove the pre-catalytic converters that are in the Exhaust Manifold.  Here is a brief summary of the problem…  Oil consumption ends up making its way to the honeycomb material of the car and causes it to break up  over time.  Then, some of these solid particles (from the cat) make their way back into the combustion chamber and cause catastrophic engine failure.

So, one of the easiest ways to solve this problem is to purchase an aftermarket header.  They are available from many sources.  I might edit this post to give a listing at some point.  But, if you want the same or better performance for cheaper, you can gut the pre-cats out of your existing exhaust manifold.  There are several write ups on the web for how to do that.  But you will need to remove the header to do so.

After you have completed the task of cleaning out the stock header or purchased an after-market one, you will need to re-install it.  Here is a list of all parts that you can replace when doing this task.  At a minimum, you will need the 3 gaskets.  And, depending on rust and other factors, you might need the other studs and nuts.

Header Parts List:

Total amount for ALL parts: $71.07 (Rough estimate based on MSRP pricing).  You might find these parts cheaper than what is listed.

I hope that helps Some of you looking to do this work.