NerdDawg.com: Installing A Flowmaster Cat Back Exhaust

As our cars get older, the problem that happens to them is that they start to have their exhaust rust out. When this happens, we are confronted with the problem of do we just change the muffler, or do we change everything.

This post will discuss how to put a cat back exhaust on your car.

Although it is not required for this task, it is best to have a second person assisting you in the assembly of the exhaust. It makes it much easier to line stuff up and make sure it fits correctly. Make sure you have your vehicle properly secured using jack stands. You should never put your life in danger when working on your car.

The first thing that you will need to do is make a decision on if you want to salvage any of the old mufflers or tail pipes. This will determine where and how you cut the pipes to enable you to get them out of the car.
In my instance, one of my mufflers had the start of some rust holes but they still worked. I figured someone could use my tailpipes at the very least. Since I wanted to save these if I could, I made sure I didn't hurt the hangers. To do this job, make sure you have a good reciprocating saw. Although a hack saw will do the job to cut the old exhuast apart, it will be a lot of work.

If you are not aware here is a picture of a reciprocating saw:

Next you will want to layout your new exhaust paring up your parts with the other. The Flowmaster kit will come with a set of U bolts for each side, the muffler with the pipe welded that connects to the catalytic converters as well as a seperate tail pipe. Make sure you lay them out the way they will go on the car so that you don't install them on the wrong side.

You will want to work with one side at a time on this.

Take your reciprocating saw and cut the pipe right after the muffler but before the rear axle. This will allow you to get the tail pipes removed from your car. You will no longer need your current tail pipes because the cat back exhaust comes with them.

Once this is done, you can remove the bolts from the back of the catyletic converters. Just a fair warning. If it has been some time since these have been changed, you may need to heat the bolts up and/or use some sort of penetrating oil to get the bolts loose. There are 2 bolts on each pipe. These are the only bolts that will need to be removed.

Next you will need to get the hanger out of the rubber hanging mount. If you have a stock exhaust, this is not necessarily an easy task. The hanger has a bit of a lip on the end and will give you problems while pulling it out. If you don't care about the exhaust at all, you could cut this and try to pull it out the other way, but I am not 100% on how well that will work. It just seems much easier than what I did. I had to get a pry bar up there and pry the hanger out of the rubber mount.

Once the muffler is out, you can start working on the tail pipe. The tail pipe also has a hanger the same way the muffler did. Again a pry bar will be very beneficial here.

Next grab your Flowmaster pipes for installation. The first thing you will notice is that the hangers don't have the lip on them. This makes installation much much much easier. The order of assmbly that I used that seemed to make the job easier was to bolt the muffler up and then slide the tail pipe over the rear axle and then hang the tail pipe. Something to remember is that you don't want to have the muffler tight until you get the tail pipe in place. Once everything is lined up then you can tighten the 2 bolts holding the pipe to the converters.

This is very important: Make sure you tighten each side a couple turns at a time to ensure a proper seal on the pipe. You don't want to have a leak.

Before you finish tightening the muffler, make sure it is straight and level. It gives a better appearance for the exhaust. Not to mention if your mufflers are not straight, you could have tail pipes at different heights out the back of your car. This is definitely not good.

Here are a few snapshots of the completed job.

this picture shows tail pipes at the same height:

This next section is actually where I had to come back and make some adjustments after the fact. I didn't pay attention to how much spacing there was between the tail pipe as it went over the rear axle and the body frame. I had less than a finger width there. This causes a problem in that when I would step on it a little bit, I heard the pipe vibrating against the frame. That is never a good sound

Note the distance between the frame and pipe

Note the distance between the frame and pipe it is kind of hard to see in this pic, but you need to look more toward the background.

This next pic shows the new U-bolt installed tightening down the exhaust. There is an argument that you should weld these two pieces together to prevent leaks, but I highly recommend getting it fit right first.