I normally like my cars to be stock simple but there is just something about having a ForTwo that makes me want to customize it. I ordered a Doug Thorley Headers
muffler from SmarTune
when they first announced their prebuy in April.
The first step was to remove the lower rear (black) valance by removing two Torx T-25 screws and two plastic rivets.
I used a putty knife to carefully lift the insert out then pull the rest of the rivet out of the body.
Looking up from under the car near the left rear whell you can see the flange that connects to old muffler to the catalytic converter. There is a heat shield that has an E-10 (external Torx) bolt connecting it to the muffler pipe (and two more screws connecting the heat shield to the top of the catalytic converter). I ordered an E-10 box wrench from Sears.com but they mysteriously cancelled my order. A 5/16" box wrench fits just fine.
The instructions say that you can reach the top of the catalytic converter from the inside of the engine compartment. But I removed the rear body panel instead (not recommended due to the extra work). Here you can see the two top E-10 bolts clearly. These must be temporarily removed in order to lift the heat shield in order to access the flange bolts.
A closer look.
Now I can finally get to the E-12 bolts using an E-12 socket with swivel adapter. Both bolts come out fairly easily once you lift the heat shield up and away from the catalytic converter. I will need to reuse the flange gasket so I carefully handle it when I take the muffler out. A generous coating of WD-40 in the rubber mounting pads helps slide the old muffler out of its pads.
The Thorley muffler is much lighter than the original.
Here you can see the E-10 bolt that was connected to the original muffler. It is not used with the new one.
Here it is installed.
With the valance back on and ready to test.
A side view.
Showing ground clearance.
And a right side view closeup.
Next I took the car for a spin. The muffler is a bit louder than OEM but has a pleasant throaty growl. The claims are that the muffler provides up to a 20% boost in low end torque. Here is their dyno test: