FMF Factory 4.1 Slip-On Exhaust - Dual [obs]

FMF Factory 4.1 Slip-On Exhaust - Dual [obs]
FMF Factory 4.1 Slip-On Exhaust - Dual [obs]

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Description See Also: 7 Reviews 6 Questions
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7 Reviews
3.9 out of 5 stars
5 Star   4 4 Star   0 3 Star   1 2 Star   2 1 Star   0
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All Reviews
Ellijay, GA
Durability 5/5 Ease of Installation 5/5 Performance 5/5 Power 5/5 Style 5/5
This product is awesome!!!!!!!

i pulled this exhaust outta the box and its way awesome! Easy install, with no problems, The performance of this exhaust is sweet, i put the 4.1 duals an a 2007 honda crf250r and changed the sprocket from a factory 51 tooth to a 50 tooth and man you can feel the power difference. Sounds awesome too! MEGA BOMB header is next! FMF ROCKS!!!!!!!!!!!!

Durability 4/5 Ease of Installation 5/5 Performance 2/5 Power 2/5 Style 4/5
Let Down

These pipes look great out of the box. Once you put them on they are a total let down. they virtually cut your bikes power in half and shorten every gear length second feels like first and third feels like second and so on. they are great to look at but dont help if you keep the 94db. insert in it helps with the power some but still is noticibly less power id recomend pro circut or a single drd or leo vince exaust

Melbourne, FL
Durability 4/5 Ease of Installation 4/5 Performance 2/5 Power 2/5 Style 4/5

I bought these pipes hoping to get a little more out of my 2007 Honda CRF 250R, but they made the bikes power decrease! It feels like the gear length is completely shortened, second gear feels like first, third gear feels like second, fourth gear feels like third and fifth feels like fourth. The only good thing about these pipes is that they make my bike look cooler.

Durability 5/5 Ease of Installation 5/5 Performance 1/5 Power 1/5 Style 5/5

I bought these thinking they would be great and add a little to the bike, the only thing it did good was save weight. Everything else it was a let down on.
It seemed to have taken power away from the bike, 3rd felt like 2nd and 4th felt like 3rd and so on. Quite a shame, they seemed absolutely wonderful before I rode it for the first time. I instantly noticed a horrible difference in power. It is way less enjoyable to ride. So bad, that I might put the stock ones back on.
Maybe I've gotten something wrong here, or this is normal for them...
They do look AMAZING and sound AMAZING though, very well built


not whats in the pic, way cooler. however, it doesnt fit with the stock gaskets, i recommend a flathead screwdriver and a hammer to "chisel" them off. then it fits very well doesnt require any sealant for riding after you remove the gaskets and slip it on. fmf does sell a hi temp sealant if you want to run sealant though.

Great buy for the money.

These pipes look sweet ,sound awesome and seem to give power gains.

Westerly RI

Great exhaust system, i am empressed with the FMF Ttanium 4.1 dual slip on, sounds sick

6 Questions
Answered:   6
Not Yet:   0
Location: Riverside, CA
Q: Does this?
Over 7 years ago
come with 2 mufflers and will it fit the stock mid pipe
Expert MotoSport Staff
Over 7 years ago Location: USA
A: This exhaust system consists of 2 canister only. You must use the Stock/OEM Mid Pipes and Head pipe to fit these dual canisters to the bike. Only the OEM mid and head pipe will work with these canisters.
Q: Is Jetting required with slip on?
Over 7 years ago
With a standard slipon and stock midpipe, is jetting necessary?
Over 7 years ago Location: murfreesboro,TN
A: when replacing pipes it would be reccomended to rejet
Q: How long do the pipes last before repacking needed?
Over 7 years ago
MotoSport Staff Expert
Over 7 years ago Location: Portland, OR
A: This depends on the type of riding and the amount of hours on the bike.

A two stroke running a little rich on the oil ratio will saturate the silencing media very quickly. On a big bore four frequent high speed riding will also shorten the life of the media. Also you should not allow water to enter the silencer outlet while washing your bike or ATV.

Let your ears be the guide.
Q: Can these pipes fit with a stock midstream and header?
Over 7 years ago
MotoSport Staff
Over 7 years ago Location: P+RTLAND
A: Yes, this pipe is to be used with your stock mid-pipe and header.
Q: Do you have to use the stock header or can i use the powerbomb header with it?
Over 8 years ago
Expert MotoSport Staff
Over 8 years ago
A: these were designed to be used with the OEM mid and head pipe.
Over 8 years ago Location: mammoth lakes
A: no you can only use the stock header. sorry bro :D
Q: What is the db from this pipe?
Over 8 years ago
MotoSport Staff
Over 8 years ago Location: Portland, OR
A: The 4.1 meets AMA specs for db's so it's going to be 98db's for most bikes. I quiet core is also available for it to drop it down even lower.
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