Both are bottle style resonators, both are similar in size, one has moar length the other moar girth. Quality to me looks comparable, as both magnaflow and vibrant seem to be decent brands for mufflers/resonators. The magna is a tiny bit cheaper.
The goal, as it is always with me, to make the car as quiet and resonance free as possibru. The catch is, I can't use the big 'ol vibrant "utra quiet" becuase it won't fit otherwise I'd use that.
I've read arguments about length vs girth, and majority seem to agree that girth is more important at killing noise, since you get more exhaust packing and whatnot.
More muffler packing volume = more better. More different lengths of those hot dog resonators = more better. Use all of them. I used both lenghts of the dynomax racing bullets as resonators in my car, I cant tell you how much it drones because the AWR mounts make it loud in the cockpit even with the stock exhaust, but combined with the borla muffler in the back they car is pretty quiet.
girth before length with mufflers/resonators. though there is a happy balance usually with real estate under a car. fit the largest one you can in the space you have available if you want to make it as quiet as you can (obvious)
if your using a muffler too, don't get a muffler under the car and another at the back. it will still resonate.
Looking at them both in hand they look the same but the perforation and the packing does different things. Mufflers quiet it down, resonators remove resonance. it really comes down to what your end goal is with adding this to the exhaust.
I just built an exhaust system for a Miata in Texas that uses the vibrant resonator above (and only that) it will be extremely loud, but it wont resonate (drone) as much as if it were a straight pipe.
Technically resonators dont have packing. When using a round glass pack, shaped like a resonator you're trying to get both the resonator effect to kill drone while also using the muffler packing to attenuate sound. I really wish I could find a good deal on a slip roll so I could start making custom fit rebuildable resonators. Its actually really easy.
I wish I had space for more tools, like a slip roll. LOL.
If your building yourself an exhaust, don't discount any spaces.
You can make a Helmholtz resonator off of the tube to tune out resonances at a specific RPM (usually highway cruising rpms). they are more effective close to the engine, but you can see them on all kinds of aftermarket exhausts from the last 10-20 years. they don't take up a lot of space and they actually work, with minimal added backpressure. many factory mufflers are straight through tubes now with these resonators inside with the muffler casing as the resonator volume.
I can make you a bottle shaped helmholtz resonator that is 4" or 5" diameter depending on what frequency you are trying to kill. That would work far better than just throwing additional "resonators" at it.
FYI - Abe @ ARTech fit one of the larger volume Vibrant resonators at the mid-pipe on my 1.6 2.5" exhaust and an "ultra quiet" resonator out back. The longer resonator fits well in the mid-pipe volume.
Thanks for the inputs guys, I appreciate it. Keep em coming of course.
I feel like I need to give you the full scenario, so here goes:
car is a '13 wrx, not a miata. I bought a really expensive and good quality Cobb exhaust for it, to replace the Invidia Q300 that's currently on there, and is a bit too loud for my tastes. The cobb is already quiet, but the one I bought is used and has a resonator on it, which is about 10" long, which is damaged (he bottomed out on a rock or something).
So now I have the opportunity to cut out this super short super thin resonator, and replace it with another one of my own choosing. The current one is thin too - only 4" in OD. I feel like I can easily fit 5" since my current invidia Q300 has a 5" resonator.
current invidia with the 5" OD resonator:
the Cobb with its tiny 4" OD resonator:
I THINK I MIGHT be able to fit a vibrant "ultra quiet" into the space I'm working with, but really not sure, and don't want to take chances.
Most resonators including the Magnaflow and Vibrant have material surrounding the inner core. The only "on paper" difference between these two is the material - The Vibrant offers a T304 Stainless Steel construction and I can tell you from experience, their stuff is easy to weld (not that I doubt Magnaflow would be).
The Magnaflow Glass pack material also doesn't have the greatest reputation for longevity. Take this with a grain of salt - Due to their large compatibility and brand awareness in the US there is obviously far more info out there about Magnaflow but a quick search turns up some pretty surprising information.
More volume gives the resonator a better ability to cancel drone, allowing the unwanted or annoying waves of sound pressure somewhere to go for better resonance throughout the system. Resonator placement comes into play when you are looking to change the tone of your exhaust but in most situations you're limited by space - Also if you're making an entire exhaust sound will also change with material, wall thickness blah blah blah.
All in all - I'd go with the Vibrant. Either direction you choose, just try to avoid placing it too close to your engine for longevity reasons (assuming a boosted application?).
If your worried about it swinging, get poly exhaust bushings. they don't sway or stretch as much.
Magnaflow and vibrant both weld fine. the magnaflow mufflers case isn't as nice and polished as a vibrant one, so it does need a flap disc clean up before you weld it.
The only thing I hate welding with exhausts is flex bellows because you cant really clean them up well enough for my standards prior to welding.
if your having a shop do the replacement, I wouldn't worry about the welding factor. lol
It sounds like you do want a muffler... to quiet it down. more than a resonator.