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So was wondering if anyone attached muffler straight from the Header. I will have the PPE header for k24. I am thinking about possibly putting motorcycle muffler, or if anyone has better recommendations? How loud is it if you have done it? For me main thing is saving weight off the back (which will get heavier with the k motor and transmission)
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Make sure you get a muffler packed with rock wool - fibreglass with just melt. Also some earplugs. Lots of earplugs.

Can confirm. Lots of earplugs. The ash tray is the perfect holder. I have assorted kinds in there. I have since changed to a more classic muffler. The 5 HP you gain is not worth it. If you want 5 HP from a 1ZZ just strap an AEM FIC to the car and bump up the timing a few degrees.
 

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It’s loud. Mine is one of the few cars you can hear all of the way around the 1.8 mile track. I am actually changing it before the series starts back up in March. Going to turn up and exit thru the center of the bumper cover above the crash bar....and add a resonator to tone it down just a little. The added benefit ifit is that when I roll off the gas going into a braking zone it will shoot the flame across the hood of anyone on my bumper!
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Mine is not pretty and quite LOUD but not earplugs needed. Top down at speed is noisy anywhichway.



Also did the mudguard duct delete, made an inlet horn with bell mounth, dropped in a sports flter and did Cap Weir´s MAF mod.
Better bottom response, still sings on the VVTi and revs more happily.
 

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thats what I dont understand... why are all those weird loops needed??? why not just do a straight muffler onto header??? if its loud, why not put bigger muffler? but that monstrosity we have from factory, with weird loops and all that is just beyond me (maybe designing engineer had something in mind, which I will never understand)
 

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The exhaust and intake are similar in the engineering stand point of keeping the engine breathing. The pulsations of the exhaust gases exiting the head are used to help tune the gases leave and assist in reducing pumping losses. There are calculations to determine the right length, size, etc. Based on the length needed, the twists and turns are needed due to the space constraints the MR2 has. You could definitely just connect the muffler to the headers, but the flow and performance will go down in theory as well as increase in noise and other things.
 

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Discussion Starter #10
The exhaust and intake are similar in the engineering stand point of keeping the engine breathing. The pulsations of the exhaust gases exiting the head are used to help tune the gases leave and assist in reducing pumping losses. There are calculations to determine the right length, size, etc. Based on the length needed, the twists and turns are needed due to the space constraints the MR2 has. You could definitely just connect the muffler to the headers, but the flow and performance will go down in theory as well as increase in noise and other things.
well I get all that, but 1) I have K24 in there, and 2) couldnt they achieve all this proper backpressure by constriction as opposed to half a mile of pipes????
 

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It also helps cool the exhaust a bit and even out all the tones before it enters the muffler. This helps keep the packing from getting melted and quiets even more. Plus the stock muffler (and any replacement you hope to keep the exhaust somewhat quiet) will be too big to just pipe straight back. And then you need space for the second cat.
 

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It also helps cool the exhaust a bit and even out all the tones before it enters the muffler. This helps keep the packing from getting melted and quiets even more. Plus the stock muffler (and any replacement you hope to keep the exhaust somewhat quiet) will be too big to just pipe straight back. And then you need space for the second cat.
well I am thinking to have 2 setups, one for cat exhaust, and one for "fun" (track, mountains etc). so wondering if the "fun" setup will be bearable for occasional daily. something along the lines of long 2.5" tube muffler packed with steel wool (technically muffler should work just like gun suppressor shouldnt it?)
 

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Call me old, but I would gladly sacrifice 5HP for an exhaust I can live with on a day to day basis. Plus most racing I do they have strict sound limits. And I like my neighbours.
I am with you on this. I replaced the CHE dual lotus as it was too noisy for me and the neighbors.
 

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I am with you on this. I replaced the CHE dual lotus as it was too noisy for me and the neighbors.
I had the same crap "Lotus" muffler. It was WAY too loud. I actually replaced it with a real Lotus muffler. Pure bliss.... much better sound and 1/8th the volume.
 

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... couldnt they achieve all this proper backpressure by constriction as opposed to half a mile of pipes????
You could, but you don't want back pressure. What you really want is back suction, to better clear the exhaust out. That is where resonance comes in. With the right length of pipe, you can theoretically get back suction when the exhaust valve is open, and back pressure when it is closed and doesn't matter. The exhaust valves are not all open or closed at the same time. That is why pipe lengths and header lengths and merging order become such a thing.
 

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The magic of tuning gas pulse. Intake and Exhaust to perform best within rpm ranges. Do it wrong and it is bad magic.

I replace the CHE with an HKS and have been satisfied with volume and sound quality. I think it was even lighter than the OEM muffler but I stopped weighing things a while back. Just driving and working on the PERMAGRIN.
 

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It’s loud. Mine is one of the few cars you can hear all of the way around the 1.8 mile track. I am actually changing it before the series starts back up in March. Going to turn up and exit thru the center of the bumper cover above the crash bar....and add a resonator to tone it down just a little. The added benefit ifit is that when I roll off the gas going into a braking zone it will shoot the flame across the hood of anyone on my bumper! View attachment 80495
funny if you cant beat em catch them on fire lol
 

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I have had really good luck with magnaflow mufflers, and they make a 2.5" inlet / outlet one with the same configuration as the OEM Spyder. Low backpressure, quiet and durable. It is what I am using on my k20.
 

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You could, but you don't want back pressure. What you really want is back suction, to better clear the exhaust out. That is where resonance comes in. With the right length of pipe, you can theoretically get back suction when the exhaust valve is open, and back pressure when it is closed and doesn't matter. The exhaust valves are not all open or closed at the same time. That is why pipe lengths and header lengths and merging order become such a thing.
Most of the exhaust tuning effects happen within the headers. Any tuning benefits or deficits you might get aft of the exhaust manifold will be much smaller magnitude; though as others have said, backpressure is the enemy.

Dave
 
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