So just got a 16 st and the previous douchnozzle straight piped it with custom 2.5 job and the drone and volume is head exploding-ly obnoxious. Been watching YouTube vids but we all know there's no representation of in person so I'd like to hear from those who have done.
What model magnaflow did you use, how loud is it and is there any drone?
Just a magnaflow muffler with no middle resonator isn't going to fully mitigate out the obnoxious 106.66hz drone that hurts everyone's ears. The problem with watching youtube videos of exhaust is that it's almost all small on-camera mics or phone mics, which have a frequency range that isn't representative of what your ears hear (or how sound pressure levels at low frequencies *feel*). Personally I have a hard time telling the difference between the thermal and other exhaust systems in youtube videos, but after getting some in-cabin high quality recordings and doing a spectrum analysis the difference was immediately visible.
Why don't you list out your priorities for an exhaust system, and we can make recommendations?
If you're trying to go super-budget, just slapping on a magnaflow will probably lead you to wanting to add a resonator, then even after spending the money for installation of a muffler and a resonator you'll wind up looking at more exhaust systems because of those 106hz pressures. If you just want quiet, see if someone has a stock system or if someone near you is planning to upgrade soon - maybe they'd let their stock one go for a couple hundred bucks. If you want a performance exhaust with no drone, the answer is almost unilaterally thermal (actively engineered to cancel the most obnoxious range), followed by CP-E (just barely misses the mark, resulting in a small amount of drone because their helmholtz chamber is just slightly undersized). I have a hard time telling from the Flowmaster videos posted so far but there isn't the 106hz spike on the spectrum analysis I did - that could mean a couple things:
- flowmaster is doing something extra and sneaky to mitigate drone, and actually did analysis and engineering of their FiST system (unlikely but not impossible - at that price point it's most likely a jig-and-weld system)
- the person recording the video is using something with mic that doesn't record the 106hz range properly (most likely)
- flowmaster's muffler tech does a sufficiently good job of breaking up those low frequencies enough to prevent wave propagation that becomes drone and secondary resonance. (possible but not likely - but I didn't know how to do spectrum analysis back in the day when I used their delta wave tech mufflers and so on, so I admittedly lack the first-hand experience).
If you're looking for a pure-muffler solution, there are a couple vendors that have focused on building quarter-wave tech into their mufflers - billy boat and corsa come to mind - but I have been unable to get responses from either when asking about mufflers and what frequency ranges they actually target. I think Corsa is only interested in selling systems (and the muffler teardowns make the insides look like they're just made of sheet-metal).
The exhaust shop that has fabbed up each revision of my self-made quarter wave resonating stuff accepted my drone mitigation spreadsheet I made for them (as well as a full how-to, from doing a customer ride-along to sample the sound frequencies to calculating the diameter and length of the required chamber) is working on developing some race/track mufflers integrating quarter wave tech, but I *think* they're specifically targeting high frequencies instead of low ones. I'm on their short list of beta testers once they get their development done, but with their use-case, I don't think it'll target the frequencies I want to target.
To be honest, personally, I'd love a 3" system that was near stock quiet but still flowed well, but that 3" diameter coupled with the length of the pipes in our system makes wave propagation an issue. If you added a couple of non-mandrel S bends into a 3" system it'd break up the waves but you'd lose some of the flow of your 3" system. That being said... if a 2.25 pinch-bent stock system is good for a pretty serious amount of HP, then a pinch-bent 3" quiet system should be too - right? I'd like to find a muffler from an M3/corvette/etc. whatever, just a stock muffler from a performance vehicle - that fits in the FiST exhaust well, and build out the piping to match the diameter of that muffler and see what happens.
