Oct 20, 2011
My S10 is a '98 4.3L ZR2. MagnaFlow does not make a header-to-post-cat piece that is for my truck, however they do make one for a '00. The difference is that the flange after the cat is a 2-bolt VS the 3-bolt that my truck had. So I went with '00 parts for both pieces. From what I can tell, there is absolutely no difference other than this flange. Pretty much made it a no-brainer switch for me. Also, the Gibson listed the off-road package in their specs. In addition, I found another member on another forum running this exact setup so I knew it would fit.
1/2" breaker bar
1/2" to 3/8" adapter
15mm socket (3/8" drive)
15mm deep socket (3/8" drive)
15mm wrench (3/8" drive)
13mm socket (3/8" drive)
13mm deep socket (3/8" drive)
14mm deep socket (3/8" drive) (for some reason, 2 of my exhaust manifold bolts were this; not sure why)
3x 6" 3/8" extensions
7/8" wrench (for oxygen sensors)
The OEM exhaust is designed to come out in 3 pieces (according to the flanges anyways): from the headers to before the cat, the cat (separately), and post-cat back. I broke the bolts that were on the post-cat flange and didn't feel like messing with the pre-cat flange bolts. I ended up cutting the pipe before the cat (after the Y-pipe), and after the muffler. REMOVE THE TRANS CROSS-MEMBER FIRST!!! (I didn't and really wish I would have) For me, this took 4 bolts on the frame, 3 on the back side of the skid-plate, 2 on the front of the skid-plate (which also hold the rubber mount to the cross-member), and 2 bolts holding the rubber bushing to the trans (these are a bit tricky to get at; do these last so you can twist the cross-member; this was the only way I could get at them). These are all 15mm. I also unbolted the 2 support brackets for the cat from the frame (just made it a little easier than prying the rubber off the hanger). These 2 brackets were held in by 2 13mm bolts each. The bolts for the flanges on the cat are also 15mm along with the nuts on the exhaust manifolds. I was lucky and got all 6 off without breaking any studs on the manifolds.
I re-used everything from the factory (nuts, bolts, rubber mounts). I also re-used the donuts that go between the headers and the downpipes. They must have been clipped in or rusted in because they wouldn't drop out. If I have leaks, I'll tighten them more or wiggle the pipes around.
I don't know what you guys think about it, but I used anti-seize on EVERY nut/bolt/stud that I removed or used.
Once you get these parts, you'll see how they go together. The MagnaFlow piece is in 2 pieces and the Gibson is in 3 pieces plus the tip. I started with the larger MagnaFlow piece. Start by putting the cat over the cross-member that holds the torsion bars and then pull it back forward to line up with the header. I just put 1 nut on to keep it held up there. Then, put on the other piece (that comes down from the driver's manifold and under the trans). I started 1 nut and then slid the pipe into the other pipe (again, you'll know what I'm talking about when you get the parts). DON'T FORGET THE CLAMP before sliding the pipes together!!!! Leave the clamp loose until the nuts are tight on the headers. Once the nuts are tight, tighten the clamp. Next, put the hanger for the cat in the rubber bushing (the OEM cat was held up by 2 hangers; this setup only uses 1...the outer one, not the inner one closes to the drive shaft). Now that that's all done, it's time to start on the Gibson cat-back. I started by feeding the tailpipe up from exit location (behind the tire). This worked great for me. Obviously, make sure the pipe goes over the rear stiffening bar or else it won't fit. With that in, and the hangers in the rubber bushings, I put the muffler on. It's marked on the INLET side. Once that's in, put the intermediate pipe in. If you forgot the clamps, don't worry. Just don't forget the gasket between the flanges. The Gibson kit uses 2 clamps (before and after the muffler) and 3rd clamp that has a hanger on it. This clamp goes just before the muffler and lines up with the rubber bushing. Neither kit comes with bolts for the flange. I went to a local store and bought stainless bolts to use; not that big of a deal. The Gibson kit does come with the gasket needed for the flange so you don't need to buy a separate one.
Hopefully this helps someone. I know its not the most descriptive, but you'll get it once you see everything yourself.
As a side note, I strongly suggest replacing the oxygen sensors when doing this. I didn't feel like fighting with getting the old ones out. Plus this way I was able to install the new ones before installing the pipes which made it a lot easier.
I apologize for bad pics, but the truck is on the ground and lighting was bad.
When the after pics were taken, I had not tightened the clamps on the cat-back sections. I needed to get the bolts for the flange before tightening everything.
I'm very happy with the fitment and can't wait to hear it!!!!!.....but that won't be for a while as my interior is still torn apart.