While I'm still unsure what's causing my engine noises - it's clear that exhaust fumes are getting into the cabin and that I need to get into the back of the engine again and check all the seals.

Since I'll be removing the manifold again... I decided to drop a little extra dough and get a new manifold.

I found a nice R manifold from Erie Volvo for a bit over $200.00. A tad expensive, but still way cheaper than the cost of the new stock model and way cheaper than IPD (Sorry guys, I'm still buying stuff from ya, just not this part!)

The new manifold arrived today. The thing looks brand new. Perfect stud threads, zero rust or grime, original Swedish cast iron performance goodness.

I've got new manifold and turbo nuts as well as the two turbo gaskets enroute. I expect the rest of the goodies to arrive on Friday.

So... aside from more efficient exhaust routing, is there anything special about installing an R manifold?

Maybe a better question is this - just what does this thing actually "do" for performance? I got it because I worry about weird cast-lines/cracks in my manifold.

Are there other "R" stock specific bits I can hunt up for this car?