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Discussion Starter · #1 ·
I just bought a stock pipe for my bike off ebay (the stocker I have is rattling inside), so I get it and look inside and holy cow..it's like all hollow and then all of a sudden the entire six-inch pipe is narrowed down into a one-inch tube!

wtf is this crap? I mean I knew stock pipes were restrictive, and I still don't like loud aftermarket pipes, but look at this thing. This is for a 929 btw.

 

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Discussion Starter · #3 ·
Re: wow--stock exhaust pipes are really restrictiv

nah, I don't need more power. The 929 already has way more than I'll ever need, but I was just shocked at how small that little hole was inside the pipe. Reminds me of the baffle they put on Aprilia airboxes.
 
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I run a Titanium Vance&Hines S4 Can on my 9 and my 426 has a full race Titanuim Exhaust too. Their both illegal for normal use and above 97db. All straight through poluting exhaust for me!
Come to think bout it both of my cars run a Pace Setter and Dual Yakamara straight through exhaust.
 

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How big of a pipe do you think you need? 350 ci small block only NEEDS approx 2 1/2 exhaust to breath (stock engine) do you think your 61 ci (1000cc) bike needs More? Do the math. Only so much air coming in...so much coming out.
 

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:lol2: :bird:--it really does suck when its only as big around as a beer can :grin: For some reason I hear my wife laughing?............
 

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eScreaming Dizbuster
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Look at the size of the valve openings in the cylinder head, and consider that the flow has to go around the valves, and that there are the valve stems blocking the middle of the ports, and the muffler doesn't look so restrictive after all.
 

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Re: wow--stock exhaust pipes are really restrictiv

How much actual horsepower do you gain by going to an aftermarket pipe? ISTR that even ten years ago horsepower gains were usually minimal with aftermarket pipes on modern sportbikes, and in some cases you even lost midrange due to reduced backpressure.

I thought the main advantage of an aftermarket pipe is reduced weight, not increased horsepower. If I am correct, then it calls into question whether or not stock pipes are truly "restrictive."
 

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Re: wow--stock exhaust pipes are really restrictiv

A Slip-on may get you up to about 3hp plus a few pounds of weight savings. A full system may get you up to 15hp (with a re-jet or new map) plus a few more pounds of weight savings. A slight loss of mid-range torque to gain the top end power is common with both. Jet or map changes can sometimes compensate for this.

Stock pipes are restrictive if your goal is peak power and you don't care how loud it is. The mid-range punch is usually more beneficial on the street.
 

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Re: wow--stock exhaust pipes are really restrictiv

[ QUOTE ]
1slowF3 said:
The mid-range punch is usually more beneficial on the street.

[/ QUOTE ]

Right, which is where most of us do most or all of our riding. If you gain 3 HP at 13k RPM, is that worth losing some midrange? How much time do you actually spend at 13k and above on the street?

This reminds me of that dyno chart of the latest 600s posted in another thread. If you just look at that peak HP, it looks like the Daytona 650 is off the pace. But it only really drops off at 12k RPM. Below that, which is where most of us ride, it's at or above the others.

How realistic are we being about sportbike power? Is a 3 HP gain at the very top of the rev range - which we almost never use - really worth spending a couple hundred $$$ on a pipe? If you have other goals (weight loss, sound, style, etc.) that is one thing, but if you're just looking for more power it doesn't pass my cost-benefit analysis.
 
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Re: wow--stock exhaust pipes are really restrictiv

Yea, when you ride your "moded 200 hp busa", 90% of the time you're only using 70-80 of those horses with most riding done at 5-7K RPM, and the peak HP being at peak rpm.
 

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Re: wow--stock exhaust pipes are really restrictiv

I opened up my pipes (before the Arrow titanium 1/2 system was installed) just to let out the growl of the Duc.

I honestly didn't really notice the Hp increase. :rolling: I suspect that if I were a world class racer, I would notice a few Hp.
 

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Discussion Starter · #18 ·
Re: wow--stock exhaust pipes are really restrictiv

[ QUOTE ]
ZOEY said:
I opened up my pipes (before the Arrow titanium 1/2 system was installed) just to let out the growl of the Duc.

I honestly didn't really notice the Hp increase. :rolling: I suspect that if I were a world class racer, I would notice a few Hp.

[/ QUOTE ]

I remember last season, Mladin's bike got a new part and he said it added 2hp, then he said "I can't notice that small of an increase though."

Food for thought for people claiming their slip-on adds noticeable power :blush:
 

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Re: wow--stock exhaust pipes are really restrictiv

It's funny how you hear the racers say that they made little changes in the setup (a mm here or there) and it made all the difference for them. Strange that they wouldn't notice a few ponies.
 

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Re: wow--stock exhaust pipes are really restrictiv

Honestly what’s 2 hp’s compared to tweaking the gearing for a certain track, or tweaking the suspension to get more bite so you can brake later into a corner. Doesn’t hp’s really come into play on the top end? I’d rather be able to put the horsies to the ground coming out of a tight corner than adding an extra mile per hour to my top end.
 
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