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I have a hole in the flex section of the rear downpipe. I took it to a muffler shop and they said they couldn’t fix it. They had some replacement flex sections but said none that would fit the car. They also said they couldn’t weld it up (as did my cage builder).
Anybody else had to deal with this? If so, how did you fix it? I need to keep the cat to remain street legal for now, so the spec exhaust is not an option.
You get a new / used one. Several people have had this happen from the spec exhaust hanging low and stressing that portion unduly.
I had a big chunk missing on the flex section of Mr. Junky’s down pipe right before the ‘V’ section. I ignored it since the hole made the exhaust sound like the Spec E30 exhaust.
I could at least pretend I was driving a Spec E30.
Anyway, I got tired of the sound when driving around town and to/from the tracks. So, I took it to a muffler shop and they wanted $100 to fix it.
I had $5 in my pocket so I got a dollar cheese burger from McD’s and bought a $2.89 exhaust pipe tape from Advanced Auto. It’s a red plastic that you wrap around the pipe.
Once heated, it turns black while fuming toxic gases and suppose to turn hard.
I’ve had it on for about 100 miles and so far it seems to be holding. I don’t know how long it’s going to last but if it fails, I’ll just get another cheese burger and another pipe tape.
Chi, hope you enjoy those cheeseburgers! The flaw in your logic is that the flex pipe is not supposed to be hard (aka rigid) like the tape you’re adding is going to be… It might last for a while, but as Jim mentioned, the correct fix is to find another one at the junkyard and eat healthy.
I had to fix this as well due to the exhaust getting beaten up at Road Atlanta after the repave, before they ground down the high spots.
TheRedBaron wrote:
Hey, I’m no stupid. If it doesn’t work after couple of times, then I’ll switch to hamburgers.
Jim,
Do you mean I need to get a new/used flex section or the whole downpipe (which includes the cat)?
I’m sure I can find the whole downpipe/cat somewhere, but I haven’t seen just the flex section available anywhere.
I found these products on the web. I’m going to check with the manufacturer and see if either will fit our cars. Looks like I might be able to replace either just the flex section or maybe the flange on the downpipe and weld in a new pipe to eliminate the cracked flex. Of course, that might cost more than just getting a new downpipe. 
TheRedBaron wrote:
FWIW I think the euro downpipes (no cats) don’t have a flex joint, so maybe the flex joint was put in place because of the cat…get rid of the cat, get rid of the need for flex???
Sean - sounds logical, but I can tell you from past experience with several cars, BMWs and others, that if you don’t have a flex something somewhere in the exhaust system, something will eventually break. My recomm, don’t eliminate the flex pipe, it serves a purpose.
Ed
Guys, its not going to be legal if you replace the stock parts with some other type of flex pipe.
Sorry on further reading is sounds like the op isn’t racing, but just a heads up for everyone else.
I’m building a car right now and I noticed that the “spec” exhaust would break my down tubes as it is not supported well at all, nor does it contain a flexible joint to avoid stressing the downtubes. I welded a new brace to my down tubes and attached it to the stock attachment point on the back of the tranny. Then directly behind that I installed a flexible joint, the style honda uses for their exhausts. It consists of 2 flanges, 2 bolts, 2 springs, and a tapered gasket. The gasket slides onto one side and the pipe on the other side is flared at a 45. The two are pressed together with the flanges, the springs are installed under the bolt heads to apply the corrent pressure to the mating surfaces. This joint can move in any direction and doesn’t leak, best part, I have never had one fail, or had an exhaust or header crack with one in use. If I had a place to post a picture I would, It is a great setup.
The spec exhaust system must be purchased from the Spec E30 approved supplier and may not be modified in any way, except minor adjustments may be made to the Spec Exhaust system to help with fitment. Any adjustment made can serve no secondary purpose.
I pasted that together from the rules. Be careful.
For what it is worth, I was able to get the exhaust fixed by getting a new flex section welded in. Basically the same as shown in the attached photo and available at any auto parts store.
Not quite the same material as the original flex, but it works. Not sure if it would be legal in Spec E30, but for now it sure is a lot quieter. I suppose if you look at the rule as quoted above, it is a change that serves no secondary purpose other than to aid fitment. Granted, it is not a change to the spec exhaust itself, but it would seem to fall within the spirit of the rule. It certainly can’t do anything to improve performance. 
Guys, I think we are overlooking a serious safety risk in regards to the fitment and craftsmanship of the spec exhaust. If our downtubes break at the flex joint, now we have a carbon monoxide leak in the engine bay. The CO will get into the cabin from there and affect the driver’s ability to perform, and at worst have him/her pass out and crash. I don’t want to retell the stories of times I’ve been at the track and seen driver’s pass out behind the wheel. The result was terminal in both cases and in one case took some else down with them. Our cars are especially damagerous as initially only the tube with the flex will break, the other will remian intact an hold the exhaust in position, so we can keep racing.
I was told that some amount of dyno tuning and research went into the development of the exhaust, and it is a nearly ideal setup for our motors running a single muffler and pipe. So why the fuss about other exhausts? As long as it is a single pipe collected at the first crossover, and uses only one muffler. If what the guys were saying is true, from a performance perspective, anything we do different exhaust wise will be at best the same as the spec exhaust. LET US RUN A SAFE EXHAUST SYSTEM!
This way with a properly fitting, hung and flexed system, our downtubes won’t break and we wont have to tamper with the stock exhaust manifold, which is were the real performance restrictor is anyway.
Can you point to the part that you have issue with on the attached picture? I don’t remember the flex section on the 325’s exhaust - I do remember it on my Honda - but - that was a very different application.
I’m not discounting your argument, but - the data points in this series are pretty high with no issues with the exhaust due to cracks due to the lack of a flex section. Also, consider that the rules allow for much more robust engine mounts than stock 325i - I would guess that this should reduce the movement that may cause the cracks you are talking about.
Also - we do drive with our windows down (at least most of us). And the Spec Exhaust is NOT for street use - matter of fact the rules forbid driving your car to the track with the Spec Exhaust, so all time with a driver in the car should be with the windows down. 
Don’t we all still have that part? I cut where the arrows show - am I missing the problem here?
