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Hi all,
Two weeks ago, our '08 Passion got really noisy, and a quick check found the flex pipe to muffler connection was broken. After doing the repair, I thought I would write about the experience and post it on the forum.
When the flex connection breaks, you have three choices, a Smart dealer, a muffler shop, or fix it yourself. I chose to do it myself.
I checked a lot of posts on the forum and the internet and found a lot of good info. I decided to replace the whole muffler instead of welding in a new flex pipe. If you have the welding equipment or someone to do the welding, it is the cheapest fix.
My first step was to pay the one year subscription fee to Evilution, it's a must for removing the body panels. They only show the European mufflers, but it still helps.
I sprayed the hangers with silicone and removed the muffler and saw that access to the flange and heat shield bolts was really tight. I did grind off the heads of the flange bolts, but then decided to remove the rear panels, crash bar, and tailgate. When you follow Evilution's rear panel removal, careful with the skirt (rocker) panel. When it says to slide it forward 5cm that's almost 2". Sliding less and you'll break most of the plastic clips (I broke 7 of 10), part # 000-991-20-98. The whole rear section comes off in one piece, then the tailgate and crash bar (#40 and #45 torx bits are required).You don't have to disconnect the tailgate wiring, just unbolt and set it in the rear of the car. Now you get the whole picture. To remove the heat shield bolts, an e-torx 6 socket, a 8mm box end or a small vise-grip should work. I used a simple propane torch and some penatrant. I replaced the e-torx bolts with some hex head, m6 x 1.00 x 12mm from Ace Hardware. To remove the flange bolts, it's whatever works. The bolts are m8 x 1.25 x30mm and take an e12 socket. Since I had cut the heads off of mine, I used penatrant, heat, and a 4" vise-grip to remove the stubs. Note, the nuts are resistance welded to the flange.
I bought a new OEM muffler (1324900015) and gasket (1321420080) on eBay and flange bolts (910143-008003) from the dealer. Install muffler then the heat shield.
Reassembly of the rear panel is fairly easy, patience, silicone spray on the panel tabs and slots, don't use excessive force. Follow the hints on Evilution.
If you choose to do the flex pipe replacement, the Walker part # is 41793 . I would cut away the old flex portion, cleanup the ends, and fit the new flex tube. I would then fir the assembly to the engine, and tack weld or match mark the pieces, remove and final weld.
The project can be very frustrating at times, but rewarding when it's done.
 

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Use stainless steel bolts and they won't rust for next time, and use flange bolts to hold down the heat shield.

Mark the exhaust pipes with alignment marks before you cut off the flex pipe
 

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Use stainless steel bolts and they won't rust for next time, and use flange bolts to hold down the heat shield.

Mark the exhaust pipes with alignment marks before you cut off the flex pipe
Due to how the three pieces fit together, I found it necessary to install them on the vehicle and tack weld them in place, then remove for final welding.

The pipes are not a snug fit in the new flex pipe, so the angle as well the depth of insertion all make a major difference in the final fit.

Although stainless steel flange-head metric bolts do exist, I could not find them in stock at my local well-equipped hardware stores, the big-box hardware stores, or Fastenal... so I resorted to the more common zinc-plated steel flange-head bolts and applied an anti-seize paste. If I was willing to wait, I probably could have gotten some off eBay.

~toaster
 

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True, you are limited by the availability of bolt in some areas, and you sometimes have to get by with what you have. If someone is planning on an exhaust replacement or repair, I was only offering an alternative material that would help combat that ever present corrosion issue all cars are prone to because of their operating environment. Locally here is and Ace hardware, and a Runnings that both carry metric sizes and a variety of different materials for bolts, and I live in a smaller town.

The ideal method to replacing the flex pipe would be to have some sort of a fixture that you could assemble the exhaust off the car and have the correct angles for the pipe and muffler, as well as the exact measurements to get the perfect alignment of the mounting flange, and location of the muffler hangers. Not too practical for doing a single exhaust. Plus the fact you are working with stainless steel parts that do need specific welding equipment to do the job correctly. Most people do not have that type of setup available to them so the best way would be to take it to an exhaust shop that makes their own pipes and systems. That may not be the least expensive way to go
 
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