CVR_Rally

Just installed one onto the 87S. One of the down pipes sits right next to part of the car so sometimes it vibrates when cold but usually not an issue. I added some exhaust wrap there to help.

I have noticed though it's a little "raspy" under certain situations. That's the best way I can describe it.

The sound comes right from the CAT as best I can tell. I buttoned up all the connections to ensure no leaks.

Does anyone else have this exhaust that can relate their experience for comparison?

Thanks Chris

curtisr

I have also installed a universal MagnaFlow catalytic converter despite not having to in my '87 924s. This was a nod to the environment. Anyways, this coupled with a Thrush full-size muffler has given the car an F1 sound at higher rpms.

V2Rocket

Did you replace the original cat with the magnaflow?
The original cat had a built-in resonator chamber of sorts which knocked down the "rasp".
Your new cat doesn't have it - it's a sound you'll learn to love...around 3800rpm in my car.

azbanks

I have one and love the sound.

CVR_Rally

I had to pull it out and put the stock back it...it still pulls great.

The main reason is the down pipe design was different and it isn't clearing the body enough and vibrates up against it. I could cut the old cat off but honestly it's running great as is so not worried about it.

Anyone want to but a barely used Magnaflow down pipe and CAT?

JacRyann

I mounted my Magnaflow CA CARB-legal oval cat at a 45-degree angle so it clears the body & heat-shields. No rubbing, no noise and the latest smog-test came in squeaky clean! Cleaner than the original-cat @ 10-years old when I started to keep those records. We'll see how the emissions numbers progress over the years.

CVR_Rally

The rubbing is from the down pipe not the CAT.

This is the complete bolt on solution they make:
https://www.magnaflow.com/products?partNumber=23796

Look how the to ends that attach to the manifold just come down then back. It's the one on the right that goes right up against the lip where the control arm is bolted. The only solution at least on my car is to grind away the mating edge on that spot, hammer it in, or hammer the pipe.

As you can see in this picture below from Lindsey Racing, the stock version has the right pipe cross over and end up on the left. This is to avoid the very problem I had.
http://www.lindseyracing.com/mm5/pics/944exh32CLL.jpg

Chris

CVR_Rally

I've fixed the area where the downpipe was rubbing and have re-installed the Magnaflow. I did have to chase the exhaust leak where the sections join but some sealant later and that's fixed.

I have checked every point and the rasp is only coming from the CAT. It's only at certain loads and clearly is just how it will sound. The old CAT wasn't really clogged but it was in rough shape. I thought about removing it as a test but I've heard the 16V doesn't like to be CATless.

CVR_Rally

I'm replying to my old thread because I went back and forth on this. Problem with my old exhaust is I think the old CAT was getting too restricted in the end. Not only was it separating around the hanger (I tried welding it) but you can hear the engine note change at idle after about 15-20 seconds after initial startup.

What I mean by that is from inside the car you could hear it get louder like it was under load. With the Magnaflow it never does this. I just wish the rattle/raspy sound wasn't there but at least it's not 100% of the time and only under loads and certain RPM.

Mister Quickie

I play a different game. I flex-piped my 951 post-turbo bypassing the cat, resonator, & muffler and saving all that weight.
Once every two years I have to swap the stock exhaust back on to pass emissions.
The flex pipe is light and maneuverable enough to direct it away from touching anything.
The 10' of 2.75" flex pipe I think cost no more than $50

V2Rocket

get that at a truckstop? lol

CVR_Rally

Luckily in CT it is emissions exempt. However I've heard that without a CAT the S is terrible. I have the entire old exhaust so I could do something with it.