[mb911]

Originally Posted by TDHarris

Ben,

Email can be overwhelming at times and my email probably fell through the cracks after an initial quick read. I've included the images I originally sent you, and will use them to answer some of the questions raised in this thread.

Yes, the headers were loosened to allow the system to "relax" during installation.
The supplied straps were used. The marks left by the straps can be seen in the image below.
The car is used 50% DE and 50% street.
No collisions of any kind.
Off-track excursions were always on smooth surfaces - no gravel traps or rocky fields.

The first image below shows the section that contacts the muffler mounting bracket. Ignoring the two small tabs that I added, it is a very flat and smooth surface. There is very little friction to prevent the muffler from shifting position. The image also shows the gussets added to the inlet pipes. Once these two modifications were made, cracking around the inlet pipes did not reappear.

Without seeing the installation first hand the skeptic can always say (with some justification), "was the system REALLY aligned properly?" The second image shows cracks around one of the end plates. There is no alignment here. The tail pipes do not touch anything! You can see a major crack following the weld seam and radiating outward. On the far right is a smaller crack working its way in from the outer weld seam. Metal too thin? Excessive harmonic vibrations?

In retrospect, I should have sent the mufffler back at the first sign of trouble. But I thought I had identified what caused the problem and how to prevent it from reoccuring. That was only partially correct - the original problem WAS corrected, but the problem moved somewhere else, and we were now on a slippery slope.

So to restate my original reasons for posting to the thread. I am looking for answers to the following questions.
1) Has anyone successfully used M&K mufflers on a DE car?
2) What is the sound level produced by current M&K mufflers? Tracks are becomming more and more restrictive. Lime Rock Park, for example, has a maximum permissible noise level of 84 dBa for cars made prior to 1979, and 81 dBa for cars made after 1979. That is not very loud. Mt. Tremblant and Calabogie are currently at 92 dBa, but are always under pressure to lower them.

Thanks again,
Tom Harris

It looks very clear to me that there are some strange harmonics going on there. That being said you should have sent it back to me before you had it modded I could have updated it to the gen 4 and up specs. That included inlet overlays and rear patch reinforcment. Though no tabs.

As to thickness etc. I have built 1000's of these mufflers all .040 wall on the shells and all .055 on the endplates. We have also added strengthing to the inlets as I stated and have even shortend the newest gen6 mufflers to keep weights downs as we have reinforced them. in that time only a handful have been returned for issues. as I stated before 99% of them were fixed and problem solve. The funny thing is you look at any other manufacturer and no one will warranty a part that has been on a track why people ask? well the heat cycling is the big thing. track use no matter 50% or 100% there is some extreme heat being produced.

that said back on topic or to answer your questions is that our latest gens are quieter then the 1st etc and even daniel jacobs is using our mufflers on his 3.6 conversions because they will meet dbs for lime rock etc. now thats not everycar but it is somewhat convincing.

Tom,

Should you want to try one of our systems again give us a call we will take care of you.