Installed a cup pipe, sport cat and SW chip recently. While at VIR, I started to hear a rattle in my secondary muffler. Upon my return I took the muffler off and there is a huge split on the inside middle of the muffler, the side away from the wheel. While I can't say it was caused by the change in exhaust, I remember hearing others had something like this happen. I took the muffler to a repair shop and they said it couldn't be repaired due to the metal being too thin.

So I am now wondering what my next step is....thoughts?

 

The outcome that you experienced unfortunately is typical of changing out the OEM muffler for the cup pipe for a car that is tracked. The suitcase muffler cannot withstand the additional exhaust pressure. Use the sport bypass cat, replace the cup pipe with OEM and use a Dansk G pipe to replace the split secondary muffler. This combination worked out very well on my former De/Street 964.

Dan

 

Hit up a few more muffler shops and ask them to repair it.

 

Splits on those are common whether you track or not. Just get it welded up and off you go!

 

I actually installed the g pipe first but didn't like the "V8" sound so went the cup pipe route and love the way it sounds. I couldn't tell any performance difference but that was seat of pants not dyno testing.

Thanks for the replies - I will search for a good used one to replace the one I have as the split is in two directions.

 

Any good qualified welder can weld the muffler, muffler shop welders do not nessecarily come into that category. Take it to a proper welding shop and have them weld it up and also reinforce it with a plate covering the welded area.

 

+1

 

It is double skinned there, they all go along that seam sooner or later!, just grind it clean and weld, done a couple now. If you are keen open it up and re-pack with fibreglass before you weld it up.

 

Get it welded by a qualified welder... mine was done by a guy who builds racing car cages and did a such beautiful job it lasted years.

 

As an update, I ended up replacing the secondary muffler with a used one sourced from a rennlister as my muffler was split in three places. Upon replacing, I noticed the heat shield next to the muffler was destroyed as it seems the heat emanating from the split in my old secondary muffler was enough to damage it. Upon further inspection, the ignition wires behind the heat shield were beginning to melt....looks like a good excuse for an upgrade. Any suggestions?

 

What model year is your 964? There was a change made to the secondary muffler during production. I will try to remember the where, what and how and post the documentation details from Porsche.

 

1990 C2

 

So on the last Sunday run to Bathurst with a few of the PFA guys from Sydney, the secondary muffler finally succumbed and I blew a decent hole in the side of it:

964-Secondary-Muffler-Blown_zpsttnbyokr.jpg

Not uncommon when running a cup pipe (which I've been running since purchase, installed by previous owner). On the plus side this opens up some exhaust options:

I'm looking at options one of which is to replace the secondary, but only if it's been updated? Mine is part number 964.111.046.04 dated 02/90 and I think the current one is .05, so presumably updated to prevent this happening again?

 

If you are looking for a OEM fitment solution to the secondary, there is this; its pricy though.
http://www.rstube.co.uk/exhaust.php?idproduit=289

 

Thanks, looks tidy, but you're right its pricey. I'm going to try a long G Pipe and put primary back on, will see how that works out.