Now since the Cruise I’ve listened to the Exhaust tracks from the videos. I mic’d the car in the back and I’m really unhappy with my current setup still. Now in the car you hear none of the rasp. That was fixed by turning the output of the muffler towards the back on the car with a factory like tailpipe.
The noise happens at about 3500 rpm and its a loud high pitch cracking/slapping noise that is completely out of place because the tone of the exhaust is quite low with the borla. So after a lot of research there are a few things I’m willing to try before completely tearing out my exhaust and redoing it (or maybe start my SC build)
I tried a homemade insert that mimics the mesh cones on the aftermarket. Most of the time put in the exhaust tips to kills the high tones. This didn’t do anything really. Probably because the holes are too large. I was hoping for the sound to bounce off the cone into the wall of the pipe.
The last thing I tried was just an experimental test for back pressure. I cut plates with descending size holes to put right behind the CAT. 2″, 1.5″, & 1″ holes. the 1.5 did a very small amount so i moved the to the 1″. You could tell there was back pressure do to the was it idled. It didn’t hinder the revving but the rasp didn’t go away or change much. So, I know this noise isn’t to do with back pressure. BTW I mic’d the exhaust and played it back with studio headphone in order to really be able to examine the sounds.
At the moment I’ve got an Auger style insert that has had mixed reviews. I’m hoping the blades will deaden the noise before it reaches the end. this is going to require me to cut out a section near the axle which needs to be 15″ of straight pipe to fit with a 3 in pipe and some reducers. After this I don’t know what I’ll do. Still on the search for something that makes a v6 with low rasp without going FI or something. I consider this a research project, so it will be a lot of trial and error.
