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Do large diameter mufflers hurt low end ?

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  #11  
Old 02-06-2019, 05:25 PM
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Originally Posted by fuelmoto
As several here noted it's not the size of the muffler body, it's the size of the baffle. Baffle size & design greatly influence & affect the overall power curve, baffles that are excessively large affect low RPM performance, response, and tunability. The M8 engine is also more picky on what it wants compared to Twin Cam. The standard 2.25" louvered baffles in the Rinehart mufflers work well in most applications, the mufflers that typically cause issues are the larger 2.5" cores, tapered, or stepped baffles that are in some of the louder mufflers being marketed.

Below is an extreme example of a Twin Cam chart showing the effects the exhaust can make on a 100Hp 107" motor.

How much HP/ torque would you say im leaving on the table by using a gutted stock pipe vs a set of your or the rinehart headers ? The way i look at it for the cost of headers i can buy a cam kit.
 
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Old 02-06-2019, 07:40 PM
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I haven't noticed any loss with mufflers , now head pipe that's a different story
 
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Old 02-06-2019, 08:16 PM
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I believe the M8 version of the 4” Rineharts are 2.5”
 
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Old 02-06-2019, 09:19 PM
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Put some TTIs in em.
 
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Old 02-06-2019, 09:21 PM
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Originally Posted by Houston_t
How much HP/ torque would you say im leaving on the table by using a gutted stock pipe vs a set of your or the rinehart headers ? The way i look at it for the cost of headers i can buy a cam kit.
The stock header with the cat removed and actually even with the cat in it is a pretty good header. When I tested cams with Steve Cole and to this day I am still running the stock header with the cat removed. The gains you'll get from a cam, air cleaner, mufflers, and dyno tune will far exceed any gain you will get from an aftermarket header and you are correct that for the price of an aftermarket header you can get a cam, tuner, and maybe a dyno tune.
 
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  #16  
Old 02-06-2019, 09:54 PM
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Originally Posted by Houston_t
How much HP/ torque would you say im leaving on the table by using a gutted stock pipe vs a set of your or the rinehart headers ? The way i look at it for the cost of headers i can buy a cam kit.
On a 107" M8 with a stock or mild aftermarket cam there are not huge differences between a gutted stock head pipe and a good aftermarket head pipe, however the differences are exponential as Hp levels increase. The muffler design also affects the characteristics of the head pipe as well.
 
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  #17  
Old 02-06-2019, 10:09 PM
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One reason to buy an aftermarket Header is if the coppers decide to defect you.......at least you can return the bike to stock easily to remove defect.....if you decat your original Header, well a decat Header you are stuck with.....

Ps- that’s applicable down here and it’s why I got a Bassani header......dunno how the coppers behave over in the States.
 
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Old 02-07-2019, 06:53 AM
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Originally Posted by 58jdn58@gmail.com
Put some TTIs in em.
Whats that ?
 
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Old 02-07-2019, 02:35 PM
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Originally Posted by Houston_t
Whats that ?
ThunderTorqueInserts. Looked up, watch some video too. Adjustable, provides back pressure, improves sound. I put some in my twinslash and it sounded a lil deeper, but haven't rode to check on performance. FWIW....
 
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Old 02-07-2019, 02:50 PM
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Originally Posted by Oz Dan
One reason to buy an aftermarket Header is if the coppers decide to defect you.......at least you can return the bike to stock easily to remove defect.....if you decat your original Header, well a decat Header you are stuck with.....

Ps- that’s applicable down here and it’s why I got a Bassani header......dunno how the coppers behave over in the States.
Well thankfully, the only coppers that are trying to police our bikes here, are the warranty police at some dealerships.

Granted, some states/cities have noise ordinances and I've seen loud bikes get ticketed before, but honestly they offenders were just begging to get pulled. Not sure the M8 would ever be in danger of a ticket like that though. lol
 
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