Currently my car is going under heavy construction. I just added the new hood and soon to add high flow cat and dual Magnaflow exhaust.
Put on a 99 model bumper to accept the dual exhaust.
5/13/2006 - Completed the build up and installation of the dual exhaust system.
I took a few extra steps in this process than what I originally intended to. I bought a high flow cat and a cat back Magnaflow dual exhaust system. The cat and exhaust system both used 2 1/4 in (inside diameter) pipes but the stock exhaust on the car is 1 7/8 in (inside diameter) so to me it seamed a bit pointless to leave the smaller diameter pipe from the exhaust header to the larger high flow cat and then back to the smaller pipe again for the exit from the cat and the sensor. So, on a whim I decided to fabricate the larger pipe from the engine back. First stop was my local muffler shop, to have them bend a piece of pipe as close as possible to the shape of the pipe from the spring loaded exhauster header coupler to the cat. They gave it a good shot but in the end I still had to modify it a bit on my own. It was a lot of work but in my opinion the result can be felt in the HP gain.
Exhaust sensor mounted into the new pipe.
The next change to the "Bolt on" system was the muffler mounts. Let me preface this by stating that there were no directions provided for this exhaust system so there might have been different ways to mount the mufflers than what was apparent to me. To me it looked like they were designed to bolt directly the back of the steal bumper bar with out any kind of vibration mounts at all. Knowing how much vibration can come from an exhaust system and adding the increased flow I didn't think this would be a wise choice for two reasons. One the after time the vibrations could weaken and eventually break the mounting straps welded to the mufflers. Two the vibrations would be transferred directly to the frame of the car causing the passengers to feel them also. Faced with this I devised another option. My car, which I found is different from most other Cavalier/Sunfire in this respect, had the factory muffler mounted to a rubber mount bolted to the frame under the car that used a flat metal tang (See picture of Mount 2) instead of a prong (See Picture of mount 1).
I went to a junk yard and picked up another mount, this is where I found out that most of the cars don't use this mount. We were then able to move the mounts from the stock position and place them where we could adjust the mufflers to mount with them. The result was a firm mount and no vibration transfer to the car. Now sound vibration is another thing, this exhaust system is monstrous and produces a deep harmonic sound, enough to blow the doors off the car next to you.
Update October 2006
The car is drivable again, maybe I'll get some more pics soon. I covered the whole trunk area with Dynomat to cut back the sound and vibrations. It helped out a bit. I also pulled off the whole exhaust system and coated it with flame proof paint (black) and then wraped it from the engine to the mufflers in black header wrap to keep the heat in. Before the exhaust coming out was cold, almost a comfortable brease. Now its hot enought to warm your hands. I also added removable silencers to each muffler. Hopefully that will keep the police happy and the neighbors from complaining and still let me have some fun when ever I take them out.
October Update # 2
Here is a small video to let you hear the sound of the exhaust system.
Also as I mentioned before here are some pictures.
Pop helping with some of the welding.
Painted engine cover
Removed expansion chamber and header wrap from the cat back to the mufflers.
Header wrap from the engine back
Header wrap from the muffler back
Picture of the dash crack I mentioned earlier.