My C5 had been stock since new and I finally decided to upgrade the exhaust system after reading an article in the July 2003 edition of Corvette Fever. They upgraded the system using TPIS long tube headers, Random Technology catalytic converters and an X-pipe. Here are my detailed instructions for performing this upgrade on my 97 Vette. Later model C5s may have different components requiring different steps. C5HowTo.com has some instructions for installing headers on a newer C5. The article in the July 2003 Corvette Fever covers the steps to perform this install as well.

My source for the parts was TBYRNE out of Massachusettes for the Random Technology part number 752722, and Corvettes of Houston out of Texas for the TPIS part number 325009. TBYRNE wouldn't have the TPIS headers in stock for 5 weeks when I placed my order in mid-June. COH had them and was willing to match the price. Many thanks to Paul at COH for understanding my urge to get these installed. As soon as he got them from TPIS, he had UPS immediately ship them to me.

According to the Corvette Fever article, this exhaust upgrade will add 40 RWHP to a stock C5. I agree!

Here's a sound clip after I completed the TPIS headers, Random Technology cats and X-pipe, and Borla Stinger install: Sound clip

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Start by getting the C5 off the ground. Raise and support the C5 using my instructions. 
 

Remove the intermediate exhaust pipe.  To do this, you must first disconnect the O2 sensor cables.  GM recommends that you disconnect the batter before performing any electrical connections/disconnections.  I left the battery hooked up and I was fine.  The connectors are located above the exhaust pipes just to the rear of where they connect to the exhaust manifolds.  Remove the blue retaining pin.
 

And, disconnect the wiring harness.
 

     Then, remove the retaining clips.
 

Now, remove the 3 nuts which hold the exhaust pipe flange to the exhaust manifold.  There are 3 nuts per exhaust pipe that need to be removed with a 15mm socket.  They are torqued to 20 Nm or 15 lb ft.  I suggest leaving one nut on each pipe, loosely, so that you can disconnect the rest of the exhaust system first.  Once all the other bolts have been removed, and the rear of the exhaust lays on the floor, you can easily undo the 2 loose nuts and lower the rest of the exhaust.
 

Then remove the exhaust bolts at the other end of the exhaust pipes.  There are 2 bolts per exhaust pipe that need to be removed with a 15mm socket.  They are torqued to 50 Nm or 37 lb ft.  My exhaust gaskets were in great shape so I'll reuse them during reassembly.
 

Then, locate the forward exhaust hanger, just behind the clutch bellhousing.  There are 2 15mm bolts that need to be removed.  They are torqued to 50 Nm or 37 lb ft.
 

Next, remove the 2 rear exhaust hanger bolts.  These require a 13mm socket.  They are also torqued to 50 Nm or 37 lb ft.
 

Undo the 2 loose nuts from the front of the exhaust assembly and lay the exhaust on the floor.
 

Slide the exhaust assembly out from under the C5 and put it out of the way.

Here are the two exhausts side by side.

Place something on the fenders of your car to prevent you from scratching the paint.

Disconnect the battery. This is necessary so you do not get a shock when you remove the alternator later on.

Place a jack under the front of the car and jack it up enough to remove the front jackstands, then let the front tires sit on the blocks or the ground. This allows for easier access to the engine compartment.

Go to the passenger side and remove the oil filler cap.

Then pull up on the plastic cover to get access to the engine.

Do the same on the driver side, but be careful as you bend the cover to get it off of the fuel line(s).

Next, identify the air valve on the driver side.

Insert a screwdriver into the plastic clam in order to free it, and remove the rubber tube from the valve.

Use a 10mm socket to remove the air valve from the air connector on the manifold.

Set the air valve aside.

On the passenger side, identify the air connection.

Remove it from the manifold using a 10mm socket. It is a metal tube which is difficult to bend and move out of the way. You're going to need to move it later on when installing the headers.

Remove the dipstick mounting bolt with a 10mm socket and pull the dipstick up out of the oil pan with a firm tug.

Next, remove the spark plug wires from the coil packs. Pull on the rubber boot, and not the wire, as the wire can separate from the boot, requiring a replacement.

Also, remove them from the spark plugs and set them aside. Again, pull on the boot and not the wire. Twisting while pulling makes it easier.

Now, disconnect the white harness connector and pull the harness retaining clips from the coil pack mounting bolts.

Use a 10mm deep socket to remove the coil pack mounting bolts. Earlier C5s, like mine, have 2 bolts per coil pack. Later ones have a mounting bracket holding them together, so remove of the bracket will be all that is required.

Set the coil packs aside.

Go to the driver side and remove the plug wires from the coil packs and the spark plugs. Again, do not pull on the wires, but use the rubber boots. The plug wire on the left can't be removed easily without the alternator away. Since we have to remove the alternator to get the new headers in, let's do this.

Back to the passenger side, use a 15mm socket and turn the tensioner toward the driver side of the car. This will loosen the serpentine belt. Pull it from the pulley.

Remove the belt from the alternator on the driver side.

Disconnect the plug at the top/back of the alternator and use a 10mm wrench to disconnect the hot wire from the alternator. WARNING: Double-check that you disconnected the battery first!

Next, use a 13mm socket and remove two alternator mounting bolts from the back of the alternator.

Then use the same socket to remove the two long alternator mounting bolts from the front of the alternator.

Use the same socket to remove the altnator mounting bracket from the engine.

The alternator is held into place very well by the bracket. Insert a pry bar or screwdriver between the bracket and the alternator to free it.

With the altnator away, have access to the plug wire on the left-most coil pack. Remove it and set it aside.

Disconnect the white coil pack harness. Remove the wiring harness retaining connectors from the coil pack mounting bolts. Then, use a 10mm socket to remove the coil packs from the valve covers and set them aside. A 10mm wrench will need to be used in order to disconnect the coil pack bolt under the fuel line(s).

Get under the car and disconnect the O2 sensor from the manifold on the driver side. It is mounted to the frame with a plastic retainer. Pull it from the frame.

Do the same with the passenger side connector.

Use a 15mm socket and remove the steering connector. Swing the steering shaft toward the driver side of the car in order to make room for the manifold removal and subsequent header installation.

Use a 10mm socket to remove the 6 bolts from the manifold. The rear-most bolt is harder to remove due to the fuel lines and vacuum hoses that are in the way, so do this first. Leave a middle bolt in place and remove it last so that the manifold is balanced and requires less effort to hold.

Pull the manifold up and away. It will require some maneuvering to do this. Hold the fuel lines away so that you don't damage the metal braid on them.

Perform the same steps on the passenger side to unbolt and extract the manifold on that side. The air tube may get in the way so pull on it to get it clear of the manifold. It doesn't seem to want to break easily, but pull on it at your own risk.

Lay everything out on the floor so that it is easier to have everything in place for reassembly.

Next, remove the O2 sensors from each manifold. Using a penetrating oil will help free them from the manifolds.

Be careful with the O2 sensors, so you don't damage them. Putting a little anti-seize on the threads is a good idea before installing them into the headers so that removal, if necessary, is easy.

Back to the passenger side, as this should be easier to install. It is necessary to remove the valve covers on some C5s in order to install the headers. With the aid of my wife, under the car and guiding the header, we were close, but not close enough, to having the headers slide right in. Use a 10mm socket to loosen the valve cover bolts. Earlier C5s have perimiter bolts, and newer C5s have center bolts. The bolts will stay in the cover with a retainer. There are two rubber tubes that will need to be removed from the valve cover. Twist and pull.

Set the cover aside and clean up the gasket if necessary.

Do the same on the driver side. However, be sure to remove the connector and retaining piece for this wiring harness. Otherwise, it will be hard to remove the valve cover. There is a rubber tube connected to the right side of the valve cover that will need to be removed. Twist and pull.

Place a towel or rag over the head to prevent the header from coming into contact with the rocker arms. Then work the header down. Having someone on the ground to guide the end of the header and inform you of what is happening down there is a good idea. The header will come in contact with the frame, oil pan, air conditioning lines and the head. It will require some pushing and wiggling and you will probably scratch the headers. I recommend not installing the O2 sensors prior to installing the headers due to all of the movement. You don't want to break it off. Don't bolt the header to anything yet, as the O2 sensors need to be installed.

Have the person under the car (in this case, the wife) remove the oil filter to allow for the driver side header to be installed. If you don't do this, the mounting flange on the header will not be able to clear the filter. There will be some oil in the lines above the filter so use a pan to catch the fluid. The 6 quarts in the oil pan will not come out when you remove the filter.

Work the driver side header down just like the passenger side, holding the fuel lines out of the way. Then, install the O2 sensors into the headers.

Use the manifold gasket that came off with the manifolds and the 6 original bolts to attach the headers to the head. Be sure to use the lock washer retainers on the bolts that came with the headers. Do not tighten this down yet.

Do the same on the passenger side. If you think it would be better to have a new manifold gasket, you can get one from the GM parts counter at your local dealer. I felt as though the old ones were clean enough to re-use.

Reinstall the driver and passenger side valve covers using a 10mm socket. Be sure that the gasket stays in the channel on the valve cover.

While on the driver side, tighten the 6 header bolts to 18 lbs-ft.

Also, reconnect the steering linkage and tighten the bolt to 25 lbs-ft.

On the passenger side, tighten those header bolts to 18 lbs-ft.

Identify the hole in the block and insert the oil dip stick. It should snap into place.

Install the retaining bolt through the dip stick mount, and into the header, so that the dip stick is secure.

Install the coil packs with the 10mm bolts and connect the wire harness white plug, and the wire harness retaining connectors.

Attach the spark plug wires to the plugs and then connect them to the coil packs.

Attach the air fitting to the header using the original 10mm bolts.

Back on the driver side, attach the coil packs, wiring harness connector and retaining connectors.

Attach the plug wires to the plugs and coil packs.

Install the air valve to the rubber hose. Install the plastic retaining ring around the hose. Attach the valve to the header using the original 10mm bolts.

Install the long front 15mm bolts into the alternator to hold it in place.

Install the rear alternator bracket to the head, and then to the back of the alternator. Now, tighten all of the bolts that hold the alternator and bracket in place.

Snap the wire harness to the top of the alternator and use a 15mm socket to reconnect the hot wire to the back of the alternator.

Slip the serpentine belt over the alternator while making sure that it is also following the original path over the other pulleys.

Once over the other pulleys, the belt can be draped over the tensioner bolt while you get your 15mm socket.

Using a 15mm socket, turn the tensioner toward the driver side and pull the belt over the tensioner. Double-check that the belt is properly mounted over the pulleys before continuing.

Jack the front of car back up so that you can now tackle the under-car work. Tighten the bolts which hold the headers to the bellhousing.

Between the headers and the frame, reconnect the O2 sensor cables.

Take one of the Random Tech cats and insert it into the header. Make sure that the O2 sensor fitting is oriented in the same position as the original exhaust. This may be a tight fit. I had to sand down the inside of the header in order to make it a smooth fit. I hammered on the back of the cat assembly with a rubber mallet while wiggling the assembly to get it installed. It only slid in about an inch.

Do the same with the other cat.

Slip the X-pipe onto the cat assembly. I had to pry my cats away from the frame as they were not close enough for the X-pipe. It will slip on easily at first but then require a lot of hammering at the ends with a rubber mallet to get it to slide all the way on.

When possible, reconnect the retaining bolts to the X-pipe. If the pipe is not forward enough, the springs on the hangers help pull the exhaust forward.

It may be necessary to wire the muffler connectors away from the X-pipe in order to get the pipe in. Continue to hammer on the rear of the pipe with a rubber mallet while wiggling the assembly until the X-pipe is firmly attached to the cat assembly.

Next, remove the 2 O2 sensors from the original exhaust.

And connect them to the new exhaust, routing the wiring back through the original channel and reconnecting the connector.

Reattach your mufflers.

Reinstall the existing filter or (like I did) put a new one on and add oil until it is full. Reinstall the oil fill cap.

While the car is up on jackstands, start it up and monitor your oil pressure to ensure that you got the filter on tight. Then let it run for a while. You will see a LOT of white smoke that smells like metal coming from the tail pipes. This is normal and should go away totally after about 30 minutes of running. You don't need to let it run that long.


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Disclaimer: 97vette.com offers the C5 HOW TO section as a guide.
97vette.com will not accept any responsibility if you make a mistake and
damage your Corvette. You assume any and all responsibility to use caution
when performing work on your Corvette to prevent yourself from causing any
damage. --Pat


 
 


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