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Caddy Exhaust Sounds

Cadillac Jim


I finally got around to putting up a WAV file for my caddy's exhaust sound. These are Borla ProXS series mufflers and a 49-state OBD II compliant high-flow cat. The IT was a bit of a project; I moved the electret microphone from my main computer to my laptop (which I rarely boot at home and don't have a place for there), found my sound hardware's application folder, set it up for the electret, and tested. I then moved the whole thing to the garage.

The car was stone cold so I let it idle for a few seconds before revving it, and the maximum RPM was 4,000. The sound file seems to have the bass coverage to give an accurate sound when I put the file on a CD and played it in my living room through my Bose 901s. It woke up my wife and all four Chihuahuas ran for cover and didn't come out for some time. It sounds a lot better in my car's Bose system.

I put the file on commercial web space. Accessing this file may not keep up with real time. If you have trouble with halts or listen to the file more than once, please download it to your computer and listen to it, or put it on a CD, from there.

Link to the big WAV file:
Caddy pipes WAV file

Bruce suggested OneDump.com and I found that 13 MB was too big. So, I cut off the part before I touched the throttle and after the engine shut off, and put a link there.
Just Business

In the process of working with the WAV file I found that it clipped quite a bit due to high low-frequency sound volume. The result is harshness that is audible on computer speakers from sound that is not audible on computer speakers. I'll make a better WAV file in the next few days and edit this post. This time, I'll warm up the car first and put the microphone ten feet from the car, not three feet. For now, both links stay up.

UPDATE August 6, 2007
It's going to be a couple of weeks before I can get to making another WAV file. There will be big changes by the time it's up, including moving over to FIOS so the download rate from my computer will be 5 MB/s instead of the 1.5 MB/s it is now. I'll have another update before I replace this entire post and the links to the existing WAV files. For now, get the long one (right click on the link, select "save" and save it to your computer), burn it to a music CD, and play it on a living room stereo with good speakers or headphones, or a Caddilac with a Bose system. The note at idle is faithful, and the clipping doesn't start until I rack the pipes.

UPDATE October 1, 2007
I moved the files to commercial web space. They should both be easier to listen to now.


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Great posts. Thanks for sharing and updating your blogs. I really appreciate it since I am really learning from all of it. Although, I haven't applied most of it with mine, the knowledge really sticks..thanks again
Lay down the blue print engine assembly and let's both work!
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Thanks, it's great to be appreciated. I need to add some new updates, though.

Regarding the exhaust sound, the key to the exhaust note is the nature of the fundamental FWD Northstar exhaust plumbing,
  • 8-2-1 exhaust manifolds, crossover, and front Y-pipe,
  • Large single catalytic converter that also acts as a resonator,
  • Long exhaust pipe down the center line,
  • Rear Y-pipe, twin mufflers, and dual twin exhaust tips.
This setup is inherently quiet as well as supportive of performance. The resonances in the plumbing ahead of the front cat provide high RPM performance. Resonances in the entire volume provide low RPM performance. And, harshness is moderated by the front Y-pipe and cat. I've listened to videos on YouTube that have been posted here that show no mufflers at all and the exhaust note is racy but not too noisy.

I got caught short by being rear-ended and both Cadillac and Borla Super Turbo mufflers were all out of stock for 90 days and got straight-through Borla Pro XS mufflers. These provide a resonance pattern identical to the stock set-up by prov8iding a resonator at the same position as the stock mufflers, but with essentially no restriction. These mufflers remove only the edge of the harshness, leaving the exhaust note you hear on the WAV files.

Of course, at WOT and high RPM, all those resonances and the exhaust port pulses that excite them are exposed, providing quite a surprise for anyone who hasn't heard it before. It intimidate me too for a few months but now I just ignore it.

At very light throttle, cars nearby can hear the exhaust note clearly enough to know the throttle setting. I have found this quite useful in handling some situations. Just staying with someone who is trying to bully you while the exhaust note shows that your car is pulling high vacuum staying with their best efforts will discourage continued bad road manners and prevent worse behavior. I've found that the "compact sport" four-cylinder crowd simply goes offline and fades back into traffic at the sound of the exhaust during engine braking in second gear, which really isn't audible inside the car. So, used properly, it can be a safety measure, too.
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