2007 Infiniti M35 Rwd. I’m running test pipes, true dual back to the stock mufflers. Anyway, sounds great, realllly torquey now too. But 2-3k rpms are crazy loud, any muffler ideas that’ll quiet that down and maybe make it pop a little more?

Possible Stillen or Magnaflow? Might be engineered a little better for when the rest of the system is open?

Did you keep the same pipe size or go bigger?
If the pipes are too big in diameter I have found it not only gets very loud at a certain RPM somewhere in that 2-3k range but also gets a lot of drone in there too. If you find the exhaust quiets significantly as you go up in RPM, this is often a sign the diameter is too large and exhaust gas cannot provide enough back pressure to negate the volume at lower engine output. A muffler wont help in this case since it is the rest of the pipe size that would need a change. Stock size is 2.25" diameter piping and I would never recommend going above 2.5" unless you are doing a race build only. 3" pipe does have a very nice deep sound that is just oh so beautiful, but it has insane drone at low RPM from lack of back pressure.


Anyway, as for mufflers themselves, you have a few options.
Glasspacks are the typical aftermarket universal mufflers you see. They tend to have a deep sound at idle and low RPM, and can get that higher frequency pop and a bit raspy sounding at higher RPM as the exhaust pressure builds.
Chambered mufflers dont sound as raspy at higher RPM,. but also dont sound as low at low RPM compared to glasspacks. These often have resonance drone though, even the dual chambered models that are supposed to reduce the drone.
Then you have turbo mufflers which I have not had personal experience with but can sound nice from the youtube clips I have heard. They seem to sound too high frequency and ricey on 4 cylinder engines, but on 6 and 8 cylinders to me they seem like the smoothest sound compared to glasspack or chambered.
Lastly, you have turbine mufflers which seem very cool to me. I really want to try one but as of yet I have no experience with them personally. These seem to have a deep sound like glasspack since the main bore of the muffler is straight through in the same manner, but also seem to have a deep throatiness as you rev. The design of a turbine muffler in a way is a combination of glasspack and chambered. It is straight through like glasspack, but instead of fiberglass material on the outside it has a chambered design directing gas flow around and then back to the center flow path.