Hopefully this will give some insight to other G37 owners that are interested in altering the sound of their exhaust via muffler delete.

Last weekend I removed the mufflers on my g37x sedan to see if I liked the way it sounded. I was happy for the most part... It sounded much more aggressive under WOT, no large differences from stock at highway cruising speeds, and there was only a very slight drone when hanging around 1500-2000RPM in 4/5th gear. However, the deepness in the tone left me wanting more. At 3000RPM and up it begins to sound aggressive, but when I am staying within 1500-2000RPM the exhaust note sounds muffled and strained like a very old beater car, especially when going up an incline. So, I told myself that I wanted a deeper tone, or at least to get rid of the strained muffled sound at ~1800RPM with something more “throaty”.

I brought the car to an exhaust shop yesterday with two ideas.

1. Attach a 2.5” steel pipe to the stock pipe where I disconnected the mufflers and finish with exhaust tips.

2. Remove the stock piping up to the OEM resonators and attach a 2.5” steel pipe from resonators to exhaust tips.

I asked what they thought, but they didn’t seem to have a strong understanding of the mechanisms that affect the exhaust sound, besides that #2 would be louder... I got quotes for both jobs and since #2 was only $25 more, I decided to take a chance and go that route. (There is another member on here that has done this, albeit with a slight modification to the resonators, and I was pleased with their results, so I figured if it wasn’t to my liking I can simply replace the OEM resonators with chambered mufflers.)

One hour later and my car is back on the ground. I start up the engine and the exhaust has a deeper idle compared to muffler delete. I pull out onto the main road and gradually accelerate to get a feel for the sound. First thing I noticed was how much “airier” it sounded, but as soon as I gave it more gas and reached 2000-3000RPM, there is a REALLY loud humming (reverberation) from directly under the cabin, which I am assuming is drone caused by the upsize in pipe diameter? I also noticed this sound when it was just the mufflers removed, but with the new sized piping, I would say the drone is at least five times louder.

I have not had much time to take the car for a spirited drive, and the weather here is going to be unfavorable until Sunday. But from driving to and from work, it seems that the problematic rpm range is 2-3k. Below 2000rpm, the exhaust sounds very similar to that of just a muffler delete. The drone begins to build at ~2500rpm and continues to get louder as rpm increases to ~3500. After 4000rpm is when the drone goes away and I get that loud aggressive sound I was expecting.

So it is supposed to be sunny this Sunday and I will be going for a longer drive. I plan to record and upload a myriad of sound clips to detail the changes in the tone within different rpm ranges.

In the meantime, I have been thinking of different solutions to fixing the way my exhaust sounds. My goal is to get rid of the loud drone and get a throatier sound, with the latter being less important.

1. Install aftermarket mufflers where the OEM mufflers used to be.

2. Replace OEM resonators with x-pipe (or similar variation)

3. Replace both OEM resonators with two-chambered mufflers. (This is exactly what user VQXauvas did to his g37x)

4. Replace both OEM resonators with two-chambered mufflers AND install aftermarket mufflers where the OEM mufflers used to be. (If I go this route, I would do it in two steps. Replace resonators with mufflers first and test the sound, then install mufflers if I feel that it is too loud.)

Thoughts? Suggestions?

 

The loud humming might be your new parts contacting the underbody.

I might suggest going to resonators that match the diameter of the rest of the tubing and be 18" inches in length.