2008 YZ450F Muffler To WR450F

Sorry if this has been answered before I dont come on here very often and a search would take forever reading through threads for a specific answer.

I want to fit a 2008 YZ450F muffler and the first section of pipe from the muffler forward, to a 2008 WR450F. Will they both fit straight on?

Thanks..

Yes, It will fit, if your talking about a complete yzf exhaust system with header.

Here's my 07 wr450f with an 08 yz450f complete exhaust.

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Best/Cheapest bolt-on power mod there is. I have an 09 yz system on my 07wr. Same as Mike above.

You should refer to the forward portion of the system as the "head pipe" so not to confuse people.

Best/Cheapest bolt-on power mod there is. I have an 09 yz system on my 07wr. Same as Mike above.

You should refer to the forward portion of the system as the "head pipe" so not to confuse people.

I do, but I wasnt talking about that section. I said the section from the muffler forward. Now that I think about it that is the header on a standard system, but I was refering to aftermarket (Pro Circuit), where there is a seperate piece before the header not permanently connected to the muffler as it is standard. Thansk for the info.

That section is generally referred to as the mid-pipe.

Mike

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There's some info here that might help you....

http://www.thumpertalk.com/forum/showpost.php?p=7086153&postcount=90

IMHO you won't see much improvement in performance without fitting a larger diameter header too. Exhaust gases are being restricted (comparitively) from the moment they leave the head.

You could put a truck muffler on it and still have the same volume of gas flowing out the end as the stocker if you still have that skinny header fitted in front of it.

Greg

After all this I sold it to my mate and the 2008 YZ muffler and 'mid pipe' wont fit on the 2008 WR. The standard header on the WR is smaller diameter than the YZ Pro Circuit mid pipe.

Best/Cheapest bolt-on power mod there is. I have an 09 yz system on my 07wr. Same as Mike above.

You should refer to the forward portion of the system as the "head pipe" so not to confuse people.

It's a well known fact on the yz forum that the 08&09 stock yz pipe gives up 7hp. That's the first thing the yz guys replace.

Where did you see that figure? 7 hp is a HUGE amount

A stock yz pipe is not that restrictive. I

I not doubting you. But im doubting the figure you were given. If im wrong.I am

i was curious about this too. i dont have a wr, but my buddy races one in beginner big bike class and its pretty much stock except i pulled the throttle restricter, pulled the grey wire, eliminated the head light and tightened the suspension as much as possible. AIS (ASI) removal kit on the way. becides exhaust, what will help this bike not be so "turd like"?

Do a search on the yz forum. Lots of posts. Send a pm to Greyracer. He's the guru that is very experienced and very smart. He will give you a complete answer.

Do a search on the yz forum. Lots of posts. Send a pm to Greyracer. He's the guru that is very experienced and very smart. He will give you a complete answer.

Just buy a YZF header for cheap off craigslist or ebay for under $50 and install that yzf exhaust and be done with it. You'll be glad you did. Best bang for the buck in my opinion.

Just buy a YZF header for cheap off craigslist or ebay for under $50 and install that yzf exhaust and be done with it. You'll be glad you did. Best bang for the buck in my opinion.

That scenario will make it worse. The best known stock exhaust is an 06 YZ 450. A complete system from an 06 is your best bang for your buck. I personally would just buy a Dr. D complete exhaust and be done with it.

That scenario will make it worse. The best known stock exhaust is an 06 YZ 450. A complete system from an 06 is your best bang for your buck. I personally would just buy a Dr. D complete exhaust and be done with it.

I've heard the 06' YZF exhaust is better then the stock 07' or 08' yzf exhaust. however, we are talking about replacing the restricted WRF exhaust though. Even an 07' or 08' yzf exhaust on a wrf will be much less restricting then the WR stocker. For us budget oriented, the yzf exhaust is good enough.

I'm happy with my 08' YZF exhaust, but if I had endless pockets I'd go aftermarket.

Where did you see that figure? 7 hp is a HUGE amount

A stock yz pipe is not that restrictive. I

I not doubting you. But im doubting the figure you were given. If im wrong.I am

The gain was not in peak HP. In that there was very little difference. The 7 HP figure was from a dyno test done by an aftermarket muffler builder using a slip-on exhaust on an '08 YZ450, and the gain came at 5000 RPM. Basically, removing the stock muffler in favor of a typical race muffler takes a pronounced dip out of the power curve at that point.

However, the discussion here is not about YZ450's. If nothing else, the '08-'09 shorty muffler is a lot lighter than the WR muffler, and at worst, I doubt it will be any more restrictive than stock. But I wouldn't anticipate any major gains unless someone who has actually run one can say otherwise based on his experience.

The pipe does require the use of the larger '08-'09 header unless some sort of step-up adapter is made for it. Overall, they aren't a great buy unless you get them cheap.

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