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Hey guys, i just put my hot bodies mgp growler on and i dont know if its just me but my bike feels like it doesnt accelerate as quick. Is this actually happening or am i imagineing it haha. it sounds awesome but i feel slower :frown2:
 

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Is there a baffle? Is it in or out?

The answer is 'maybe'. Slip-ons usually do very little, but they can change exhaust volume (therefore velocity) slightly from stock, but it's not a big effect - all the gubbins and the diameter of the stock headers do most of that.

There is a psychological effect in that the bike is much louder, but you aren't going any faster, so you can feel something has been lost.
 

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Maybe you might need an ECU tune or get a new ECU
http://www.ninja300.net/ninja/300/ecu/ninja-300-ecu.html

The stock exhaust typically do not flow straight.

Aftermarket exhaust usually have "straight flow" so they do tend to give different flow compare to the stock one.

I could not find Ninja 300's exhaust flow diagram, but it's very typical to see something like this:


Aftermarket exhausts are usually more efficient
http://www.twobros.com/Exhaust/
 

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I put on a Coffman's slip-on last month and could tell right away that I lost power down low. Even with their "baffle" (if you want to call it that) in, I could tell I lost power. I do a lot of freeway commuting and listening to a slip-on on the the 300 for 25 minutes straight at 9000 RPM gets old very fast. Between the insanely loud four-wheeler growl and the lost power, I put the stock exhaust back on yesterday. As soon as I took off with the stock muffler back on, it felt like I gained 10 HP - no joke. I guess I just have to live with the sewing machine sound of this bike or go buy myself a 636 and lose half of my MPG's and drop another $6000 :grin2:
 

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I put on a Coffman's slip-on last month and could tell right away that I lost power down low. Even with their "baffle" (if you want to call it that) in, I could tell I lost power. I do a lot of freeway commuting and listening to a slip-on on the the 300 for 25 minutes straight at 9000 RPM gets old very fast. Between the insanely loud four-wheeler growl and the lost power, I put the stock exhaust back on yesterday. As soon as I took off with the stock muffler back on, it felt like I gained 10 HP - no joke. I guess I just have to live with the sewing machine sound of this bike or go buy myself a 636 and lose half of my MPG's and drop another $6000 :grin2:
That makes sense. I think low-midrange is where you're going to feel it due the loss of scavenging.

The other solution - outside of a 636 - is to get some of that exhaust velocity back and throw air and fuel at the problem, in the form of a tuner or ecu flash.
 

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Full system with a tune will gain some horses.

A slip on will usually be only as good as stock, or an imperceptible improvement. Tuning can give a smoother power curve though in any case by running a little richer low down and a little leaner high up.
 

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so the slip on will lose power and full exhaust will gain power?
Negatory. A slip on will not change your power/torque curve. It will only make your bike sound better. A full exhaust system can give your bike the extra power only if you tune your bike.
 

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That makes sense. I think low-midrange is where you're going to feel it due the loss of scavenging.

The other solution - outside of a 636 - is to get some of that exhaust velocity back and throw air and fuel at the problem, in the form of a tuner or ecu flash.
Yeah I thought about flash-tune and gearing my 300 down so it wasn't so annoying on the freeway but I think I am just going to wait it out and buy a 636. There are so many 2013/2014 636's in my area that are sitting at the dealerships NEW marked down to under $8000 it is driving me crazy!
 

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Negatory. A slip on will not change your power/torque curve. It will only make your bike sound better. A full exhaust system can give your bike the extra power only if you tune your bike.
I have no proof but I can 100% tell you that the slip-on I had killed my low-end power. I am sure if I had the ECU flashed to match the exhaust it would have made things better but my slip-on by itself absolutely affected my acceleration. But each slip-on is different and mine was a shorty (essentially straight pipe) by Coffman's. The big canister styles like the Musarri, Yoshi, or Two Brothers might not be as bad...
 

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I have no proof but I can 100% tell you that the slip-on I had killed my low-end power. I am sure if I had the ECU flashed to match the exhaust it would have made things better but my slip-on by itself absolutely affected my acceleration. But each slip-on is different and mine was a shorty (essentially straight pipe) by Coffman's. The big canister styles like the Musarri, Yoshi, or Two Brothers might not be as bad...
Just a slip-on right? Catalytic converter, stock headers still there? Make sure there aren't any leaks. Check both ends of the header and header/exhaust connections. That's weird...a simple, straight pipe slip-on shouldn't pose these types of problems.
 

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I'm so confused now.

People are saying slip ons make absolutely no difference...

So, what if you get Yoshimura exhaust manifold and keep the stock silencer? Would it make just as much power as "full" exhaust?
 

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I'm so confused now.

People are saying slip ons make absolutely no difference...

So, what if you get Yoshimura exhaust manifold and keep the stock silencer? Would it make just as much power as "full" exhaust?
No, it would restrict things too much. Think of the whole system from the manifold to the muffler. There's tonnes of info on the subject, e.g. this is a good thread:

http://www.xs650.com/forum/showthread.php?t=19056

Here's a primer about back pressure, among other things.

http://www.gomog.com/allmorgan/exhaustbackpressure.html

It's all about your tune.
 

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I'm so confused now.

People are saying slip ons make absolutely no difference...

So, what if you get Yoshimura exhaust manifold and keep the stock silencer? Would it make just as much power as "full" exhaust?
interested as well
would like the benifit of a full system and the silence of the stock .
dont like ringing the dinner bell for law enforcement.
 

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The Italian Exhaust-Manufacturer Leovince, who is known to deliver the most powerful full-exhaust system for the EX250-FI, gives the following statement:
"The dB-killer supplied in the box can be used to optimize the performance."
The exhaust comes delivered with the dB-eater number 32B and the one in the box is the dB-killer number 32BF, please see the attached pictures.
While the dB-eater is 'fully' open the dB-killer has only 12 holes the let the exhaust gases stream out, with optimizing the power.
 

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I thought back pressure was needed for 2 stroke engine but not 4 stroke?

That's why 2 stroke engines have exhaust chamber...
 

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The design of a good exhaust system is one of the biggest science in the construction of an engine.
And it is true that a 4-stroke engine is not so extremely dependent on backpressure as a 2-stroke engine is.
But the simple problem is that a very correct backpressure or the right backpressure is needed because this causes the oscillation of the exhaust gas and when this does not exist the engine produces less power.
Timpo, make a very simple test for yourself, which costs you nothing.
Deinstall the complete exhaust system and then ride your bike - you won't experience a real high speed run.
! Very important, do this far away from any civilization where no one can hear you.
A well designed complete exhaust system will bring more power than any ECU-Mapping can ever do, but at least it's also important to say, that ALL components MUST fit together since it's never only one part what makes the system working.
 

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Exactly that is your problem - not enough backpressure.
+1 on this ^. When I had my 300 and put a M4 slip on on the bike I could immediately tell that it had lost low end power. It was noticable from stock. Then I did some research and heard about back pressure and bought a baffle for the exhaust. Upon installing the baffle the bike felt 'normal' again. I eventually tuned the bike with the area P tuner and only the slip on, K&N filter, and snorkel delete and it did smooth out the power curve and made another slight but noticable difference, especially for me being in the mountains at higher altitude where the bike is already bogged down. But all that still wasn't enough power for me so I sold the 300 after a year and bought a 2013 Z1000 naked street fighter. Power problem fixed!??

 
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