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How I Installed the KR Mufflers

Discussion in 'How-To' started by 6-Speed, Feb 3, 2009.

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  1. 6-Speed

    6-Speed Member Established Member

    Oct 16, 2007
    The KR mufflers (Ford Racing PN M-5230-S) are pretty ratty looking right out of the box with lots of residue on both ends - probably a byproduct of welding.


    A TS member previously wrote about cleaning the ends with an Aluminum polish so I decided to give it a try. I used Mothers Mag and Aluminum polish and cleaned off the ends. Real easy process and it makes the mufflers look way better.

    I also heard from a reliable source that windex works pretty good too.


  2. 6-Speed

    6-Speed Member Established Member

    Oct 16, 2007
    The muffler I installed on the driver's side is the one on the top as shown in this photo - note the rear hanger pin is installed higher up on the pipe (closer to the inlet end). Everything fit and aligned properly so I assume this is correct.


    Here are the tools & supplies I used to install the mufflers:
    1. 13mm combination wrench with a ratcheting box end (this will be your friend while removing stock mufflers - a very useful tool)
    2. 16mm combination wrench
    3. 3/8" ratchet wrench with 13mm (deep & std), 15mm & 16mm deep sockets and an extension.
    4. 3/8" Torque wrench.
    5. Anti-sieze (optional)

    I backed up my car onto ramps to raise the rear end up allowing more room to work under the car. Apply the parking brake and block the front tires.

    I started by removing/replacing the stock muffler on the passenger's side.

    1. Loosen the muffler clamp with a 16mm deep socket or wrench.


    2. Loosen and remove the two bolts on the front hanger/isolator. I used a 13mm ratcheting box-end combination wrench, which helps tremendously. The side bolt is not visible so you'll have to loosen it by feel.


    3. Loosen the two bolts on the rear hanger/isolator and remove the side bolt leaving the bottom bolt attached (but loose) to support the muffler.


    4. Make sure the muffler clamp is loose enough, then support the muffler body and remove the remaining rear hanger bolt and carefully wrestle the muffler out.

    5. Transfer the two hanger/isolators to the new muffler - this is the passenger's side muffler.


    6. This step is optional - I applied a small amount of anti-sieze to the threads of the four hanger/isolator bolts. I heard of one person breaking off a bolt while attempting to loosen it; this is to prevent that from happening.

    7. Insert the intermediate pipe into the new muffler inlet and install the side bolt into the rear hanger; the side bolt is more difficult to align and is easier to do without the bottom bolt installed. Once the side bolt is started and finger tight, install the bottom bolt finger tight. This will hold the muffler in place. The KR muffler body is much smaller than the stock ones so there is more room to work when re-installing the hangers.


    8. Install the side bolt into the front hanger. Once the side bolt is started and finger tight, install the bottom bolt finger tight. Tighten down all the bolts enough to secure the two hangers - I torqued these later.

    9. The muffler inlet pipe must be mated to the intermediate pipe end such that the button bottoms out in the notch on the muffler end (see picture below). Then tighten the clamp with a 15mm socket. I torqued the clamp bolt to 40 lb-ft in a two-step increment - first to 35 lb-ft and then to 40 lb-ft.

    You can see in the pictures below that there's much more room to work under there and access the hanger bolts with the smaller mufflers.

    NEW_MFLR_CLAMP.jpg Button_Notch.jpg

    10. Finally I torqued the four hanger/isolator bolts to 18 lb-ft.

    11. Repeat steps with driver's side muffler (photos below). I have heard that on some cars, one of the two driver's side muffler hanger/isolators is mounted with three bolts instead of two.



    Make sure the tips do not come into contact with the plastic diffuser. The tips on my car centered up well so no tip alignment was neccessary on my part.

    You'll notice the difference as soon as you fire up the engine. I am very happy with these mufflers!
    Last edited: Feb 3, 2009
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