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full or slip-on

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getting a yosh for my 09 crf450r. how much better would the full system be than just the slip-on?

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Its pretty tough to make more power with a header on these bikes. The stock one is pretty damn good.

Kinda depends on what it is youre trying to accomplish.

A slip on and a good map on that bike makes a bunch of power.

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I had an rs4 full system with a map. Crunched the yosh header and threw my stock header back on.

Noticed absolutely no difference between the full system compared to stock header with the rs4 s/o.

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not trying to be an ass, but my vote is leave the exhaust stock, and save your money for tires! that bike is already capable of going faster than 99% of the general public that will ever ride it. you can do more with tires/gearing/proper technique than you ever will with an exhaust. sorry, but thats just how it is. (my opinion of course. and your money)

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My view and experience is a little different that stated above. If you are a MX rider on short tracks stock is the way to go.

If you ride dunes or open trails aftermarket is the ticket. This is based on top end performance.

A good pipe will net more top speed and top end power than stock any day.

We have compared several pipes and have had great results on top end power.

The MRD pipe is a great pipe, especially the top end pipe. We compared the two pipes against one another and the top end pipe did not lose much bottom and really screams on top.

We found the top end pipe could get us 97.8MPH and the stock only 92.

In a drag race the top end pipe gave the bike about 2 bikes at the finish line.

The only difference between the pipes that I can see is the header length and diameter.

I picked up a WB aluminum pipe with a very short header. The thing absolutely screams on top. The can's packing was gone, the header has a dent in it and it suffered on the bottom end. The extra power on top made up for the losses on the bottom. Use this for MX, hell no. Dune pipe, hell yes. It rocked.

We tried it against the MRD and the MRD had slightly less on the top but made up for it in the mid to win.

I took the header from the WB and mated it to a procircuit pipe. The hybrid... The pipe was a monster! The PC was a slip on with the stock header. The pipe would not sing on top. It did have a top speed of 97 with the PC pipe and stock header but it took longer to get there.

I realize these bikes are not designed for drag racing but we are bored and have fun doing it. Those that run the dunes can get some added performance from a shorter system with a larger diameter.

Look carefully at any system you buy and keep in mind where the power will be based on the header length, diameter and any steps in it. The larger the header diameter and shortness the less bottom end.

I perceive that most exhaust manufacturers are designing pipes with the most power under the turn with some top end in mind due to the nature of what a MX bike was made for.

I would not hesitate to run the bottom end pipe on the MX track. If the bottom end pipe is to much you can use the top end pipe to mellow out the bike if you have to much power.

My .02

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i agree with all that. im just saying that i would rather have brand new tires LOL. play riding is one thing. but, on a track, you would be hard pressed to improve lap times with an exhaust. you can definitely move the power around with a pipe. but to make "more" power without taking it from somewhere else with just a pipe? nope. you will need to tear into the motor. the top end pipe to mellow out the bottem end is a good tip though. especially for guys that get fatigued easy/quick (myself included).

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bye the way, what kind of gearing are you running to go 90+ MPH? and what year bike? the OP was referring to an 09'.

14/48 most of the time. MX 13/48.

Bikes we have tested are 2003, 2004, 2006, 2007, 2008 CRF450R.

We swap pipes and roll on race many times using a GPS to log speed.

I don't think it matters what year bike as long as you can tune the A/F properly.

There is some science to pipe length, taper and diameter, reverse cone and steps. Unfortunately I don't know much about the cause and effect of all the variables. The idea is to use the sonic wave of the exhaust pulse to help reduce the pressure on the piston and have good pulse timing during overlap. It is only for a narrow RPM band that happens at different multiples of RPM.

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i was looking for more overrev out of my 2009. I got a great deal on a full yoshimura system. from my experience the PC and yosh pipes were best for my bike but in the end i went with yosh.

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i was looking for more overrev out of my 2009. I got a great deal on a full yoshimura system. from my experience the PC and yosh pipes were best for my bike but in the end i went with yosh.

You'll want to get the ECU remapped too. You'll notice it for sure and its relatively cheap. Contact Yosh.

Or Eddie Sisneros. Id contact Eddie first...

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Here's my two cents for what it is worth. I have both, Yosh slip on and full titanium system on my 09 450. Stock works fine for motocross. The slip on increased the low end and made it easier to come out of corners with more torque to clear a short approach jump. The full system comes on hard and pulls like crazy. I took the full system off and run the slip on at the track. The full system is good for desert, dunes, or what we do in the winter snowbiking because of the extra power. The slip on comes with a spark arrestor and 96 db insert so you are legal when you need to be. For the money I would do a slip on, not to many people I know can ride a 450 to it's potential and if the can they are getting paid.

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Great thread....nice to have dialogue between fellow enthusiasts and have people share their points of view without a bunch of insults. Very cool.

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