What materials are used in stock exhaust?
 

Pulling apart the underside of my '99 to for a clutch, IMS, and RMS replacement. The underside and exhaust components were in generally good shape (42K miles and vehicle sat in the garage a lot for the past decade).

Exhaust bolts etc were a little rusty but came free with a little penetrating oil and patience.

The midpipes and muffler are dull and have some light surface rust in some areas. I'd like to clean things up and/or refinish and have a few questions:
1. Stock manifolds are cast iron, correct?
2. Muffler is stainless, correct? What about the u-pipes and clamps?
3. What about the midpipe and cat housings? Stainless?

The bolts that are pressed into the midpipes are a little rusty. They could be re-used but would prefer to replace them. Any words of advice about if that's possible?

All the components you mentioned, are 309 stainless steel. Parts that get hotter, will look darker. The mid pipe bolts can be pressed out ( penetrating oil and bench vice with a socket will do the job). Replace them with SS (304 grade preferably) bolt and nuts.

You may want to put in a stud kit for the installation of manifolds

Thanks for the info -- perfect. I will clean things up and try pressing the studs -- and replace with stainless!

FYI since may be helpful to others. I rented a tie rod puller from O'Reilly's ($45 deposit which is refunded when you return it). It worked perfectly to push the bolts out of the midpipes with minimal drama and no need to pound things with a hammer.

My '99 is exceptionally clean underneath. Spent most of it's life in a barn when not driven it's 40K miles in northern CA and Boise, ID. But the exhaust bolts were too rusty for my taste.

It's definitely been a good day. Also extracted the manifold bolts without any drama or breakage. Heads were rusty but hadn't lost their shape. Soaked them in penetrating oil for a few days and used my 1/4 drive cordless impact driver on 'em. Easy-peasy...