K&N, Air Tube, and Throttle Body Installation

1. Disconnect your negative battery cable.
2. Remove the air box cover and stock air filter.
3. Remove the three bolts holding the air box to the wheel well.
4. Loosen the screw clamp holding the air tube to the throttle body and remove the air tube.
5. Using torx bits and sockets, remove all electrical connectors and fittings from the throttle body. You may want to label them, but each will only fit in one place on the throttle body.
6. Slide the throttle cable and throttle return spring off the throttle body spring. Be careful, and don't break the plastic couplings.
7. Pop off the cruise control cable if you have one.
8. Remove the four torx screws holding the throttle body to the intake manifold and remove the throttle body. Remove the gasket as well and keep it as a spare if it is in good shape.
9. Spray some brake or carb cleaner on a rag and clean the throttle body mounting area.
10. Install the new Turbo City throttle body and new gasket (supplied). Install all electrical connectors and fittings as well.
11. Reinstall the throttle cable, throttle return spring, and cruise control cable.
12. Loosen the two screw clamps on the end of the Turbo City Air Tube.
13. Install the Air Tube by placing the open end over the throttle body and clipping the support bracket into the forwardmost throttle cable clamp on the valve cover.
14. Tighten the screw clamps connecting the Air Tube to the throttle body.
15. Place the K&N filter on the end of the Air Tube and tighten the screw clamp.

I did this installation while on my lunch hour at work.  I had experience in working with the throttle body when replacing the exhaust manifold on my 91 YJ, so it may take a bit longer for the novice.  It should not take more than two hours at the most.  As you can see from the pictures, it really opens up a lot of room in the engine compartment, which I have since used to install a York air compressor.  I like the look of the K&N and tube filter as well...it's kind of "high tech".

I installed the cat-back system (see below) a few days after getting the above components, so I got a chance to see how much of a difference they would make in the Jeep's performance.  And what a difference there was! 

From a stop, the throttle is much more responsive.  Now I'm not saying its like Tom & Jerry where they take off so fast their heads are left behind, but it definitely improves pickup between 0-20 mph.  Above that, power increase was small at best, except there was a noticeable jump of power in 3rd gear.  Right around 30 mph the throttle was really on the ball. 

Read on to find out how much the exhaust contributed to the TJ's power.

Cat-Back Exhaust Installation

1. Loosen all the bolts from the stock exhaust piping, starting at the lower end of the exhaust manifold.  Also unbolt the exhaust hangars from the frame.
2. The pipe between the stock muffler and the catalytic converter has a pin holding it in.  Use a dremel or grinder to remove the head of the pin and then remove the remaining pin material.
3. The stock exhaust directly behind the cat will not have to be "peeled" off the cat exit tube. 
4. Twist the muffler and slide it off the cat.
5. Hilift the rear bumper to provide more clearance between the rear axle and body , then maneuver the muffler and remaining tubing out.
6. Pre-assemble the new setup.  By doing this, I realized a 2.5" muffler bracket was missing.  Instead, an extra 2.25" bracket was included.  A run to the auto store produced a new 2.5" clamp.
7. Work the loosely-fitted assembly over the axle and roughly into place.
8. Tighten all brackets and reattach all spring hangars.

The installation was quite easy.  It took about two hours with a friend assisting and the proper tools.  Other than the dremel, it really only required basic hand tools.

 

   

The exhaust pipe provided with the cat-back is mandrel bent and
much more resistant to corrosion than the stock piping.

   

The tubing conforms nicely to the limited space around the rear end.

   

Here is the final installation.  The muffler looks, sounds, and performs great!

The cat-back system sure lets you know it is there as soon as you start up the vehicle!  Rumble, Rumble and you have got one mean sounding Jeep!  The sound is very nice, and not too loud.  Throaty, but not so loud as to cause a nuisance.  I have heard many an exhaust system that annoyed me late at night.  On the freeway, the sound is barely noticeable and a low volume stereo drowns it right out.  It did not cause any noticeable vibrations inside the vehicle, either.

I drove around the neighborhood at speeds up to about 25 mph, stopping and starting to feel low speed differences.  It had the same pep off the line as with the modifications at the top of the page, but I could not feel any real power increases. 

I drove out to the freeway and opened it up.  On the way to the freeway, in the mid-speed ranges, the pick up was quite noticeable.  Again, 3rd gear seemed to be the largest benefactor.  The gas pedal really felt lively, especially when RPM's reached about 1800.  On the freeway, a bit of a power increase was evident.  Fifth gear was still not restored completely (it was not expected to be), but was more useful on short hills. 

I can't estimate how many HP were added by installing the Turbo City Performance Kit, but Turbo City claims about 30 can be gained.  That would easily punch the TJ up over the 200 HP mark.

I am extremely impressed with the bolt-on performance Turbo City has assembled in this kit.  It can be installed in an afternoon and looks, sounds, and performs to advertised expectations.  The individual parts of the kit are available seperately, so you can upgrade one part at a time as money or time permits. 

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