06-05-2020, 04:30 PM | #1 |
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Has anyone removed secondary cats and resonator?
Referencing the US spec here.
The stock exhaust has two secondary cats and a big resonator box in the midpipe before the muffler. As far as I know, the AA midpipe deletes the secondary cats and resonator and replaces it with a single, 3.5" pipe, correct? As an alternative, has anyone simply cut out the resonator and secondary cats to replace them with straight piping? If so, how does it sound? |
06-05-2020, 05:57 PM | #2 | |
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The mid section does quite a bit for silencing the car It really takes virtually all of the sharp tone out of the exhaust's audio profile It sounds like you're thinking of something other than the aa mid so I can't really speak on just cutting out the secondary's and the resonator. But it's definitely worth every penny for the aa mid. |
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06-05-2020, 08:08 PM | #3 | |
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Drives: M3CX
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06-05-2020, 08:22 PM | #4 | ||
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No tune |
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06-05-2020, 08:39 PM | #5 |
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sweet - I am close to AA I will drop by and have them install!
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06-05-2020, 08:43 PM | #6 |
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06-06-2020, 02:17 AM | #7 |
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US spec model - I initially installed cat-less downpipes and had both secondary cats and the resonator removed - stock muffler left in place. I liked it because it sounded pretty good with the valves open but was still pretty quiet with them closed. However, with the valves closed, there was a slight metallic vibration at around 1700 RPM under moderate load. No big deal. Well, after around 1000 miles, the valves continued to loosen up. It started buzzing and rattling at nearly any RPM under load, even with the valves open. I just had the valves removed and the muffler gutted two weeks ago. It is the way to go. Much cheaper than buying and installing a built system, and I think it sounds better. It's quite loud, though, so if that's an issue, steer clear. I also just disabled active sound today. What a difference. So much quieter in the cabin under all conditions, sounds much more natural. Also no more fake burbles. It now naturally releases a short, snarly salvo of pops when I transition off the throttle between shifts, and it rumbles down on deceleration from about 1700 to 1000 RPM. I am also running BM3 Stage 2 (AGG) 93 octane tune. I never was fond of the S55's exhaust note, but I can say I love how mine sounds now. It's how it's meant to be. Aggressive, loud, and non-synthetic.
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06-06-2020, 06:33 AM | #8 | |
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Did you just replace the resonator with two independent straight pipes or did you build an x-pipe? |
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06-06-2020, 07:16 PM | #9 |
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Yes, the secondary cats and resonator were replaced with separate straight pipes. No x or h-pipe. A balance point may give better exhaust note, but it doesn't really have any performance benefit on a turbocharged engine, so I didn't do it.
I do have a few videos! The mods are in the description. The buzzing is pretty obvious, but it got much worse over time. I need to make some new videos with the current setup (no valves, empty muffler, active sound disabled. Those burbles are ridiculous and serve no purpose). |
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06-06-2020, 11:18 PM | #10 | |
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