Two things that made the job go a little easier when i did mine were:

1. Dropping the whole exhaust so that the stubborn cat flange could be wrestled with in a more comfortable location (ie, a bench instead of flat on your back).

2. Bolt the new header pipe to the cat before attaching the header pipe to the exhaust manifold. It took some head scratching to figure this one out, otherwise the holes in the flange might not look like they want to line up. ...Got my Bosal from the partsbin and it fit fine.

hi there. i replaced mine last weekend. i purchased one from fcp groton, it was not fabricated for a perfect fit. i could have sent it back but i did not. i had to heat the pipe and bend pipe two times to make the flange line up to the cat. the material of the header pipe was pretty good quality. (you wrote from exaust manifold to intermediate muffler) doesnt your car have a cat?. my car is a 3rd car. so i was able to spray the bolts once a day for seven days with p.b. blaster. and the bolts broke free pretty easily. (if you spray oil on this part everyday and then drive it might catch fire? i dont know) i got one price from a muffler shop it was 250.00$. so i had to do the job myself. thats my experience. good luck

The job is awkward and dirty, but it is a bolt-on affair. You'll want to get new gaskets for cat flange and manifold-to-header. The nuts should be replaced on the those, but I find it strange the dealer "has to order them". You'll run into stubborn, rusted cat flange bolts and nuts. Count on sawing them out. This is where a dremel tool can be a real timesaver. Make sure you have a set of hardware to replace them. Check out the midpoint mounting bracket. I've had to do a bit of Sunday-evening hacking after discovering the bolts and bracket were too far gone to re-use. You'll want a long extension and, I think, 15mm socket to reach the manifold attachment nuts. They should be lock nuts, but the metal interference type, not nylon inserts.

No welding necessary if Starla supplies you with a decent part. Have had no trouble with Bosal. Never was able to afford genuine Volvo.
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Art Benstein near Baltimore

If your downpipe and cat are OEM, it's a bolt-on. You'll need three new copper nuts for the manifold studs, and probably three bolts/nuts/lock washers for the catalytic converter connection. And of course you'll want to get the gaskets for each end of the front pipe.