Mazda 2 custom exhaust design

MUZZA

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2014 MAZDA CX-5 Maxx Sport 2.5Ltr AWD + 2008 MAZDA 2 DE GENKI
Hi All,

Im am in need of some advice on a custom exhaust system installed today on my 2007 M2 DE Genki 5-speed.

The exhaust specs are as follows:
- 2" mild steel press bent from the cat back
- resinator
- 4"x8.5"x13.5" straight through, glass packed oval muffler
- muffler has an internal 'dog leg' bend in it so it's a O/C inlet and outlet and is 2" internal.
- 3" dump tip.

The remainder of the engine remains stock.

The result I was after is a slight 'hum' over the OEM exhaust with a higher flow.
Definately nothing loud!!!! More of an OEM sound.

Unfortunately, on the drive home from the exhaust shop, it's way too loud for me.
The car is now has a drone at around 90Kp/h (55mp/h) and also a drone while coasting downhill in 4th gear.



Can anyone suggest what may be the issue here;
- the 2" piping (should I have stayed with the OE size of 1.75")
OR
- the design and/or size of muffler?

I had originally asked for a 6" round muffler with a 2" internal, but was only offered the above muffler when I arrived.
The above new exhaust specs were under the advice from the exhaust fabricator.



Please feel free to let me know any thoughts, advice and/or suggestions.


Thanks in advance.
Muz
 
Where is the exhaust tip? If it is anywhere near under the car it will cause the sound to reverberate under the car which makes it louder inside. When I first made my axle back it was really loud. I then put a 4" extension on the outlet so the outlet wasn't under the bumper at all and it is a lot quieter. It could also be the muffler. The one you mention doesn't seem that large and especially if it is a straight through it is going to be louder. A good chambered muffler is your friend. I am a fan of magnaflow's mufflers. I use them for all of my cars.
 
I can almost guarantee it's the straight through muffler. Nearly every car I've ever been in with that type of muffler has drone. +1 on the Magnaflow chambered.
 
Where is the exhaust tip? If it is anywhere near under the car it will cause the sound to reverberate under the car which makes it louder inside. When I first made my axle back it was really loud. I then put a 4" extension on the outlet so the outlet wasn't under the bumper at all and it is a lot quieter. It could also be the muffler. The one you mention doesn't seem that large and especially if it is a straight through it is going to be louder. A good chambered muffler is your friend. I am a fan of magnaflow's mufflers. I use them for all of my cars.

The tip exits directly under the exhaust outlet moulded into the rear bumper. Where the OEM tip exits.
Yeah the muffler leaves ALOT of room where the OEM muffler used to sit.
 
I can almost guarantee it's the straight through muffler. Nearly every car I've ever been in with that type of muffler has drone. +1 on the Magnaflow chambered.

It's booked in next week to have a 'glass packed tri flow/reverse flow' muffler swapped in.
Approximately the same size.

I have read chambered mufflers can give off a 'metallic' note in the rev range.
I was advised the glass packed tri flow muffler will still retain a deep note, but ALOT quiter than the straight through muffler.
 
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Heeey NICE build on both cars mate.
I love the dual exhaust.

Help me out with this detail...
my car currently has a polished chrome 3" dump tip. Do you think this looks ok or a dual 3" straight cut welded to the single outlet from the oval muffler.
I may look into painting either matte black down the track. Just for kind of a racecar look.

I am looking into ordering the CS SRI and duct aswel as the rear torsion bar.
Worth the $$??? Im trying to build mine on a massively tight budget.
 
Here is a video from outside of my car after adding the extension. Any shorter than this and it was quite loud inside because much of the sound was under the car. You can see somewhat where I welded it onto the muffler. That was where I originally had my outlet. It was just a little past the starting edge of the muffler cutout.


Don't forget about DDMWorks. We have intakes and rear bars as well.

Zach
 
Muzza....

Got this to fit on Julie's M2 Tamura...

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Shaun....
 
Ok, an update...

The rear straight through muffler was swapped out for a glass packed triple flow/reverse flow muffler, (the chambered type of design) still 2" internal diameter.
This has resulted in a much quieter exhaust, subtle until you open up the throttle.

The only issue now is we fitted a 3.5" dump tip rather than the 3" dump tip from before.
But, it was welded directly to the muffler body without a reducer cone. The exhaust note now 'flutters' around within the tip giving a 'hollow' sound.

I have requested either a reducer cone be fitted or the original 3" tip be refitted.

(If I work out how to upload pics, I will share how it now looks.)
Happy with how it looks, but just not 100% happy with the 'fluttery' sound.
 
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Good Idea, will try in the next few days, although, free-revving it without load isn't really and accurate indication.
Will still have a go at it anyways.
 
What is the stock piping size? I was thinking to have a muffler shop make me a cat-back.
 
What is the stock piping size? I was thinking to have a muffler shop make me a cat-back.

For the 1.5Ltr, I think it's around 1.5" diameter, it may reduce down to 1.25" inside the OE rear muffler.
 
Had this same issue, went to a 12 inch resonator instead of that joke now it sounds really good unless im cruising at 70
 
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