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Yoshimura RS-4 Full System 2009 crf 450

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I have heard nothing but good things about the Yosh system. I personally have the Pro Circuit TI-4R system on my '09, and love it. The top end and overrev with this pipe is far improved over stock, which I think it needed in a big way. I'm sure you can't go wrong with most any of these pipes on the

'09, as I think it needs one!

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i was woundering if anyone has the Yoshimura RS-4 Full System iam looking to buy a full system and cant make my mind up which one to get i had the fmf 4.1 with mega bomb on my 08 and liked the top end it gave it

I have a Ti w/carbon end cap i might be selling.It only has about 10 hrs on it.

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i have used the yosh and the pro circuit. I just switched to PC Ti4r it does have great top end, but it gives up some low end in comparision to the yosh. I bought another yosh pipe yesterday. The mid on the yosh is superior. The PC pipe is SUPER DUPER quiet however. Surprisingly quiet. And quick for such a quiet pipe. I doubt if the yosh would be that fast with the 94db insert. The pipe diameter on the PC is a little larger than the yosh.

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i was woundering if anyone has the Yoshimura RS-4 Full System iam looking to buy a full system and cant make my mind up which one to get i had the fmf 4.1 with mega bomb on my 08 and liked the top end it gave it

My Ti/Ti RS-4 is still waiting to be mounted. I simply haven't had the time to put everything back together yet. It is a work of art however - very well put together for what that is worth. Sharpest/cleanest manufacturing that I've had on an aftermarket exhaust yet - I've had Pro Circuit, White Brothers, FMF. This is the best LOOKING from a engineering/manufacturing view.

Comes complete with a custom Yoshi wash plug & sticker kit. Nice touch.

No comment on performance yet but soon I hope.

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I have a stock pipe and I smoke guys with a full yosh. Every weekend.

So I have had good results with the stock pipe

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Red out of the Yosh and the PC which would you feel would be better for the novice rider since you used both and have seat of the pants feel. i know your pro speed but for a slower guy?

i have used the yosh and the pro circuit. I just switched to PC Ti4r it does have great top end, but it gives up some low end in comparision to the yosh. I bought another yosh pipe yesterday. The mid on the yosh is superior. The PC pipe is SUPER DUPER quiet however. Surprisingly quiet. And quick for such a quiet pipe. I doubt if the yosh would be that fast with the 94db insert. The pipe diameter on the PC is a little larger than the yosh.

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Prob the PC pipe. It gives up some low end compared to the yosh, great for throttle control if you havent got an easy wrist the yosh will blow out berms really easily. PC pipe you dont have to shift as much it just revs forever. I just like all the power I can get Im 6'4" and 205 with no gear on.

BTW, I have that PC Ti4R pipe for sale, only got one ride on it. PM me if you're interested.

img00154.jpg

img00155t.jpg

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I got the Yosh full ti system. I noticed increased off idle pull and greater over rev. I have to have Eddie remap for the new pipe, as it is leaner now then with the stocker.

Like H Bomb I'm 6'3" 205 I need all the hp I can get. I'm happy with what the Yosh did for me.

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There is another link that I gave my 1st impression of the Yoshi RS-4 exhaust. Here is the link: http://www.thumpertalk.com/forum/showthread.php?t=749633

I can now elaborate on that impression though. I did drop one tooth on the rear sprocket to allow for better throttle control due to the huge gain in HP and torque. It is AWESOME now! The smaller rear sprocket now allows for the throttle control but because the YOSH added so much more power in the mid and top end, it can still pull each gear better. There was also an article in the latest MXA which gave some dyno data. I took that data and graphed it if anyone is interested (see below). The graph is just a little scewed because MXA only did readings at certain RPM's so the actual peak horsepower is very close to the Pro Circuit. IMO you can't go wrong with either the PC or Yosh systems but if you like low end and midrange, the Yosh appears to be better. The max HP is slightly higher on the PC (PC = 54.9, Yosh = 54.3) but gives up a little low and mid.

MXA Dyno Data.jpg

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There is another link that I gave my 1st impression of the Yoshi RS-4 exhaust. Here is the link: http://www.thumpertalk.com/forum/showthread.php?t=749633

I can now elaborate on that impression though. I did drop one tooth on the rear sprocket to allow for better throttle control due to the huge gain in HP and torque. It is AWESOME now! The smaller rear sprocket now allows for the throttle control but because the YOSH added so much more power in the mid and top end, it can still pull each gear better. There was also an article in the latest MXA which gave some dyno data. I took that data and graphed it if anyone is interested (see below). The graph is just a little scewed because MXA only did readings at certain RPM's so the actual peak horsepower is very close to the Pro Circuit. IMO you can't go wrong with either the PC or Yosh systems but if you like low end and midrange, the Yosh appears to be better. The max HP is slightly higher on the PC (PC = 54.9, Yosh = 54.3) but gives up a little low and mid.

Haven't seen that graph before. Very eery that the FMF and Yoshi are carbon-copies of one another on the Dyno. Same for the DRD and Y&H. Seems odd that they are so exact. PC is the differentiated one but might primarily benefit the faster riders.

I need to get my RS-4 mounted and out on the track for spring. DAMN the job and I need to get the family to coorperate!

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Haven't seen that graph before. Very eery that the FMF and Yoshi are carbon-copies of one another on the Dyno. Same for the DRD and Y&H. Seems odd that they are so exact. PC is the differentiated one but might primarily benefit the faster riders.

I need to get my RS-4 mounted and out on the track for spring. DAMN the job and I need to get the family to coorperate!

I did the graph using just the raw dyno data that MXA provided. Watch me get hit with some bogus plagiarism (had to look up that word) suit.

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Haven't seen that graph before. Very eery that the FMF and Yoshi are carbon-copies of one another on the Dyno. Same for the DRD and Y&H. Seems odd that they are so exact. PC is the differentiated one but might primarily benefit the faster riders.

I need to get my RS-4 mounted and out on the track for spring. DAMN the job and I need to get the family to coorperate!

Look at the DB ratings for all the pipes.The Yosh is the only one over 100db.If you put an insert in it to makle it the same as the FMF or PC i wonder how the performance would be affected?

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Yoshimura has a insert that makes it 94db but they clame no power loss but we all know thats hard to belive

More like impossible to believe.

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Yoshimura has a insert that makes it 94db but they clame no power loss but we all know thats hard to belive

MDK did some exhaust testing and said that the Yosh with the insert in did not perform as well as the PC or FMF with there inserts in.I wonder how the FMF would run without the insert?

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I have just the RS-4 s/o with a map from Eddie and noticed a considerable difference from mid to top over the stock set up. This is with no insert whatsoever though, and yes, it is loud as hell.

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