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Discussion Starter #1
This isn’t specific to M5, but I’m hoping that someone can shed some useful info.
I have a 2017 Acura TLX 2.4 4cyl. I just had the primary cat removed (catless downpipe) and a custom catback exhaust installed. The exhaust goes from 2.5” section with a vibrant bullet resonator into a Y, splitting into 2.25” dual exhaust with magnaflow straight through mufflers.
The exhaust tone is nice and deep, but it’s way to loud up to 4K RPM. Inside the cabin things are ratting from the sound. I’m not sure if it’s just the volume or the low bass note. I told the shop I wanted it to be quiet...lol.
How can I fix it? The exhaust shop told me I can put in another vibrant resonator (super silent model) but that’s only going to reduce the volume by 20%. The second option is the change the mufflers to buffled type.
Is that a better option, or maybe another muffler after the resonator like Flowmaster super hp2.
I’ve been reading a bit and it seems that there is some strategy when tuning exhaust, but I don’t have the expertise.
I’m going to try and attach the pictures of the exhaust.
 

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can't see the pic... so I assume you have have a glass pack cherry bomb type muffler, which really isn't a muffler but a straight pipe maybe with one baffle and fiber glass. A muffler one the other hand isn't a always a straight pipe but instead a bunch of baffles and tubes surrounded by fiber glass or some type of packing.

Obviously the less baffles and more direct flow the louder it'll be. Your best option is an actual muffler flowmaster or borla are actually pretty good despite being associated with American muscle.

I'm attaching a picture I found to give you an idea about design and sound, it's some marketing stuff but it should give you an idea.
 

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Discussion Starter #4
The pictures do show up on my phone and desktop, second post only.

Any specific recommendations in terms of muffler make and model?
I found this on LS1 tech, it seems that Borla XS is the quietest with decent performance results. However this is dating back to 2009.
The results in HP order:
1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Sound Off in Quietest to Loudest (Decibels):

1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).
 

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As you can see you're looking at about 1-3 hp affect. Mufflers really aren't a big restriction esp compared to Cats and header design, I mean bad bends ect can effect it but it's pretty much a negligible differences between quality products.



It really comes down to sound and price. If it were me , I'd search clips audio clips for people with the TLX to get an idea of what you like and how much you're willing to spend.



That goes for all cars btw ;)
 

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Discussion Starter #6
As you can see you're looking at about 1-3 hp affect. Mufflers really aren't a big restriction esp compared to Cats and header design, I mean bad bends ect can effect it but it's pretty much a negligible differences between quality products.



It really comes down to sound and price. If it were me , I'd search clips audio clips for people with the TLX to get an idea of what you like and how much you're willing to spend.



That goes for all cars btw ;)
I appreciate the recommendation, however this is uncharted territory. There simply are next to no 4cyl TLXs with exhaust mods, some v6.
I've already spent way to much on this exhaust, and want to manage the financial bleeding. I was hoping to go back to the exhaust shop knowing exactly what I need.
At this point I'm thinking I should have left the stock exhaust in with the catless downpipe, and just had the tips put on.
Oh well, I was told $200 to replace the mufflers with "some" baffled type. I think I'll jut go with their recommendation.
 

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Discussion Starter #7 (Edited)
As you can see you're looking at about 1-3 hp affect. Mufflers really aren't a big restriction esp compared to Cats and header design, I mean bad bends ect can effect it but it's pretty much a negligible differences between quality products.



It really comes down to sound and price. If it were me , I'd search clips audio clips for people with the TLX to get an idea of what you like and how much you're willing to spend.



That goes for all cars btw ;)
I appreciate the recommendation, however this is uncharted territory. There simply are next to no 4cyl TLXs with exhaust mods, some v6.
I've already spent way to much on this exhaust, and want to manage the financial bleeding. I was hoping to go back to the exhaust shop knowing exactly what I need.
At this point I'm thinking I should have left the stock exhaust in with the catless downpipe, and just had the tips put on.
Oh well, I was told $200 to replace the mufflers with "some" baffled type. I think I'll just go with their recommendation and maybe change the resonator to the "super silent" one.
 

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Discussion Starter #9 (Edited)
I couldn't find anything online to help decide on the ultimate options. I went back to the shop to get the mufflers changed and another resonator put in.
The difference is marginal. There is this deep tone vibration in the cabin up to 4k RPM. My wife also say it's too loud outside...I could probably live with it, but not the noise inside the cabin. I've read about some noise/vibration cancellation strategies, but in the end it's still too loud outside and "happy wife=happy life". Her exact words where it sounds like a race car...lol
As I see it I really have the following options:
1. Replace the Y with a single-in-to-dual out muffler, and hope that cures it. This is what the factory setup consists off.
2. Reinstall the factory catback, get the quad tips put on and hope that it sounds fine with the catless downpipe.
3. Put the catted downpipe back, with the existing exhaust and hope it's quite enough (least favorite, the downpipe is worth 10-15HP)
4. Return both the downpipe and catback back to factory, and install the tips. (least favorite, the downpipe is worth 10-15HP)

The boy racer in me is wanting to give it one more try and do the option one. It would also be such a waste having spent now almost $2K on this exhaust, just to trow it all away.
Recommendations? Am I foolish to think the added muffler will help cure the drone?
 
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