Toyota 4Runner Topsites

Exhaust System Page


Borla Cat-Back Exhaust System
TRD Cat-Back Exhaust System
Other Cat-Back Exhaust Systems
Edelbrock Exhaust Headers
TRD Exhaust Headers

Borla Cat-Back Exhaust System:

The quickest and easiest thing that I did was install a Borla Cat-back Exhaust system. I purchased the system from Performance Products. The system came with a how-to video that explained how to remove the old system and install the new system. The removal of the old system is straight forward and took about ten minutes. The new system would have gone on in about the same time, but I hit a snag. I was unable to install the oxygen sensor in the port provided due to a sloppy weld. I had to take the connector pipe back off and enlarge the hole with a file.

It is real dirty. I took this pic just before I took it off.

Once everything was installed, I started it up. Wow, it sure did sound nice! Was there any increase in performance? Probably, but nothing real noticeable. This is one of those "personal satisfaction" modifications. If it does not sound right, nothing else matters.

I am planning on removing my TRD Cat-Back and reinstalling my Borla Cat-Back system. I also am planning on changing the tip to a dual Borla Carbon Fiber Tip. I have seen some of these tips installed on project cars in magazines and they look very nice. The problem is these Borla has these tips made for them and the supply is very limited. I am told it will take 10 weeks to get it in.

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TRD Cat-Back Exhaust System:

Borla makes this exhaust system for TRD. I had heard that TRD was going to stop using Borla as a supplier and switch to another company. I was at Conicelli Toyota picking up my TRD headers and found out that they had the Borla made TRD system in stock so I grabbed it.

I have heard that TRD is having Tri-Flow make there new systems for them. I have not seen one and can not comment about it.

The TRD system looks like that factory system except for it uses a Borla muffler and has a nice tip that goes straight out the back instead the side. It also uses the same type of OEM flange connections.

It is a real nice system and installs easily. It sounds just like the Borla Cat-back.

I am having a few problems with it. The flange that connects the muffler section to the tail pipe section rubs and vibrates against my rear Addco sway bar. The tip also bangs on the underside of the bumper when I hit large bumps. These problems are driving me nuts. I was planning to make some modifications to correct the problems, but then I had a thought, why. I have a perfectly good Borla cat-back that is completely free of problems. I am going to remove the TRD Cat-back and reinstall my Borla cat-back soon.

Please no emails asking for my TRD cat-back, it is promised to my brother.

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Other Cat-Back Exhaust Systems:

Here is a picture of the GReedy Cat-Back system. Go to M-n-M's web page for more information and pictures.

Here is a picture of Charlie's home made exhaust system. Charlie has seen what the huge exhaust tips have done for those little tiny Hondas and figures this mod is good for at least 100 HP, but he thinks he might have lost about 3/4 lb-ft of torque. All he needs now is some high temp paint.

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Edelbrock Exhaust Headers:


Looking for still more performance, I decided to install the exhaust headers from Edelbrock. When I unpacked the box the headers came in, I thought to myself that this should be easy. I set aside an afternoon and got started (it took two days).

The first thing I tried to do was to remove the crossover pipe. The crossover pipe connects the left exhaust manifold with the right one. I started to remove the three nuts on the back of the right manifold where the crossover pipe attaches. I got each nut about half way off and each of them seized. I could not get them off with a six-point socket. The nuts started to round off. I tried tightening them back up, and no luck. They simply would not budge. I used a torch and tried to heat the nuts hoping that they would release. They still would not budge. Well now I was committed. I could not tighten everything back up and forget it, it had to come off now.

Out came a bigger torch. I flame cut all of the nuts and studs that held the crossover pipe to both manifolds. I then removed all of the nuts that held the manifolds to the heads. There was not enough clearance to remove anything. Everything was binding up. It is real obvious that everything is pre-assembled prior to installing the engine in the vehicle. The installation instructions that came with the headers said that the crossover pipe could be removed by guiding it toward the passenger side and then down toward the frame. Well, I had no such luck. Everything was one big bind. It was clear that I had to cut the ends off of the crossover pipe. I did not flame cut the ends off because I did not want to cause any heat damage to anything else. We decided to use an arc welder as a cutting torch. It worked great. The ends of the crossover pipe were off and I did not set anything on fire. I have recently learned that the preferred method is to use an air powered chisel to chop off the ends.

Once the ends of the crossover pipe were off the pipe came right out like Edlebrock said it would. The manifolds slipped off. I then removed the down pipe, which on the 4Runner contains the catalytic converter. The old system was off.

The new system slips right into place without any fuss. The only snag was the bottom nut on the center tube of the left header has to be started before the header is seated. This is because the end of the stud comes real close to the center pipe, and with the header seated there is not enough clearance to start the nut. Of course I did not figure this out until I had everything else tightened down. It is also almost impossible to get a wrench onto this same nut to tighten it down. It turned out to be a two-man job. I reached up from underneath blindly with a wrench while my helper reached around the center pipe with two fingers and guided the wrench onto the nut. I was able to get at most a 1/8th of a turn at a time. Then the process starts over. It took at least an hour to get this one nut tightened down. All of the rest of them went with good access with box end wrenches.

The next step was to attach the "Y" pipe. It is similar to the stock crossover pipe, but goes underneath the transmission and is a snap to install. It has a down pipe that comes from each header and turns into a "Y". There is a flange at the end of the "Y" that connects to the catalytic converter. There is a port built into the "Y" for the front oxygen sensor.

The next step is to attach the catalytic converter. On the Tacoma and the T-100 it is a no brainer. On those vehicles the converter bolts into the system at both ends. This is not the case on the 4Runner. On the 4Runner the converter is in basically the same place, but it dose not have a joint on the front. The converter and the down pipe is one part. You have to take careful measurements and cut the front of the converter off. Then weld on a flange that is included in the kit. Once this flange is welded onto the front of the converter, it will bolt into the system.

The instructions then say to start it up and let it idle without driving it. Allow it to come up to operating temperature, and then shut it down. After cooling down completely everything is tightened up again. Then comes the test drive.

It is immediately apparent that there is an improvement in performance. It was really more that I expected. I think it is most enjoyable at highway speeds. Just the slightest touch of the throttle yields instant response and acceleration. There is more power and torque noticeable at all speeds. Unfortunately, that pretty black finish goes right up in smoke!

Aside from the supercharger, the Edelbrock headers were the single most noticeable increase in overall performance. It is also the most cost effective performance item I installed. However, when I factor in the difficulty of installation, I wonder if it was worth it. If I had to do it over again I would. I do want to make it very clear that the installation is a serious job. I am pretty good with turning wrenches and my good friend Tim is a professional mechanic. We had all of the tools, MIG welder, lifts, and access to Tim’s shop for two days. I believe that if we did this installation again we could complete it in one afternoon, because all of the questions have been answered. I do recommend that you do some serious thinking before you take this project on. If you do, and get it completed you will be very happy. I do have a tip, pay someone to do it for you!

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TRD Exhaust Headers:

TRD originally was going to have Edelbrock make their headers system for them. I even have one of the original TRD catalogues with a picture of the Edelbrock headers in it. No one will say what happened to the deal between TRD and Edelbrock.

TRD had Thorley headers design the header system for them. I will tell you they are really something. They are a bright stainless steel with cast stainless steel flanges. They are really the nicest looking headers I have ever seen and I just had to have them.

I do not know if it is true or not, but I have been told that Thorley designed the headers and TRD has contracted with several different manufacturers to make the headers for them.

I got mine from Conicelli Toyota. I brought them home and pulled them out of the box and stuck them together in my basement for some pictures. I am sorry they did not come out very good. I then boxed them back up and shipped them to Performance Coatings to have them ceramic coated in black satin. They look really nice.

I went to remove the Edlebrock headers and was having trouble getting to that one nut that gave me fits during the installation. I got fed up and used a Saws-All and cut the primary tubes off of the driver’s side header. After that it was a snap to remove.

There are a few tricks to the installation of the TRD headers and overall I think the installation instructions really suck. The headers include soft copper gaskets and the instructions say to also use Permatex high temp copper silicone sealant on all of the gaskets. Ron had his TRD headers professionally installed and he told me that he had heard from several people that their headers leaked. He said the key to a leak free installation is to use LOTS of silicone. So I did. I got that stuff all over everything.

The biggest tip is to pay someone else to install them for you, but if you insist on doing it yourself here are the few tips I have that should make your life easier:

  • You will have to bend the brake line toward the fender to be able to slip in the passenger side header.
  • Rotate the driver’s side header 90 degrees clock wise and start to guide the header collector down the side of the engine and along the side of the bell housing. Reach your left hand down between the engine and the firewall from the top and grab the collector. Pull it around and behind the cylinder head while rotating the header clockwise and into position. It will fit but you will have to be patient.
  • Do not tighten down any of the flange bolts until the whole system is together.
  • The driver’s side header is in two pieces. After the main piece is installed you will have to install the separate tube that goes from the front exhaust port to the "drop out" flange behind the engine. It is a little tough to get it onto the exhaust port studs and the dropout flange studs at the same time, but again it will work. Now this is the biggest tip of all. The drop out flange nuts are a real PITA to install and tighten down. The best tool to use is a 13 mm flex socket in inch drive with a long extension. I used a piece of electrical tape and jammed the nuts into the socket and then approached the studs from the brake vacuum booster. They go right on and with that combination of tools they tighten right up.
  • The down tube installs without any problem. The large nuts and bolts included with the headers are made so that you do not have to use a wrench on the other side while tightening everything down. Real nice hardware!
  • I found that the flange that bolts to the front of the cat is a little lower and to the more to the side of the vehicle then the stock down pipe. To clear the frame with the cat I had to weld the flange a little off center. I did not like the way this turned out and I am going to redo it as soon as I get another flange from TRD. I have been told it is on the way.
  • If you get the copper silicone all over the place do not try to wipe it up. Let it cure and rub it off the next day.

I found that other then the dropout flange all the nuts and bolts are real easy to get to and tighten up, not like the Edelbrock headers. I think you will find that all the bad things I said about removing the stock system will still apply here. The nice thing is I had already removed the stock system for the Edlebrock installation.

In comparing the two header systems I would have to say that the TRD headers perform better and is a higher quality system, but costs about twice as much. I would say if money is an issue just stay with the stock system, if not go TRD.

I had planned on doing before and after dyno tests to compare the Edlebrock to the TRD headers. While installing the TRD headers I also upgraded the fuel injectors and adjusted the valves. I could not do a fair comparison on the dyno with so many changes. I will say that seat of the pants in cruise the TRD headers perform better and would install them again.

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