I recently installed the full Magnaflow OEM grade Y pipe and stainless exhaust system on my 04. I like the performance and it runs nicely. My issue is the occasional drone.

At first it was pretty harsh but the sound has softened over 400+ miles which Magnaflow told me would be the case. It still has a drone that comes and goes. I've switched from the dual tip to the single turndown. This morning I put the dual tip back on to see if that would make a differences but haven't driven it yet. I was curious what others have done to address the drone and if there is a preference for the turn down tip versus the dual outlet just below the bumper.

Thanks for your feedback and help.

 

I think we have the same set up. I have a complete Magnaflow setup (Y-pipe/cats/muffler) I have run this setup for 40K+ miles. I remember when it was first installed regretting the decision because the groan was more than anticipated especially on the highway. I had the dual tip installed. I researched adding a second muffler like Rover to quite the groan. I never did anything. I took the advice of turning up the stereo. While that solved the problem short-term the overall groan has subsided. I don't remember how many miles I logged before the groan was reduced but it does quite down.

 

Thanks for the feedback. I did a quick drive yesterday and the twin tip seems better. My sense is that the slightly longer pipe couped with the twin openings diffuses the sound. As I mentioned, Magnaflow said that they expect the sound to settle down over time as the stainless is heat treated and the muffle packing settles in with the actual exhaust flow. Time will tell whether is gets quieter or I just get used to it.

 

I’ve been wanting to do this on my P38 for a while, but haven’t got to it yet. In theory, making a Helmholtz Resonator should do the trick.
https://wilhelmraceworks.com/blog/drone-reduction

 

Looks like that could work but as it applies to my 04, I get the sense that I'm headed in the right direction by driving it. I seem to hear a drone at 1750 rpm's but, again, time will tell if that settles down or I just lose my hearing...

 

The drone on my P38 is around 2100 rpm. Right at slower highway speeds. It can be annoying. Faster or slower are fine.

 

Here's an update for those interested. I have about 1,100 miles on my set-up and it is much better. I think that it takes time for the stainless steel tubing and muffler materials to settle in and reduce the harshness that was there when brand new. I still have some drone at 1750 rpms but overall, I'm pretty happy. At this point I'd recommend the MagnaFlow system but beware that it will take some drive time (an longer drive distances/time) to heat treat the material.

 

I don't have the magnaflow system but I removed the rear resonator and swapped the main muffler for Magnaflow 12256 and I have a drone at ~50mph but overall the exhaust note sounds so much better than factory!

 

I have about 50K on my Magnaflow system. After about 10K I got underneath and torqued everything down again. I also have the twin pipes. It's much more muted now than when I first installed it.

 

I agree and plan on inspecting and re-tightening at my next O&F change. Thank you for the insights.