Duncan Fatboy 4

[Phoenix78]

Does anyone have the Fatboy 4 yet? If so:

Pro's and Con's???
How did it change your power curve? Low, mid, top?
What air filter are you running?
Did you mod your airbox lid?
How loud is it compared to other aftermarket exhausts?

Any info is greatly appreciated!

[kazpr]

Ya I am starting to dig the DR pipe alot also. They say 22% gain in hp seems pretty good if true!!

[RobRacing]

I got one on mine. It fit very nicely and there are really no cons except for the header gets discolored. I noticed a lot of gain on the bottom and mid but haven't been able to do a top end run. It is hella lound! Not sure how much louder than other pipes but it is definatly loud. But it sounds sweet. I just completly removed my air box lid. I am running the stock filter but am going to get a twin air here soon so I can dial in the jetting. Hope this helps.

[kazpr]

Just got off of the phone with DR seems like that is the one I will be going with also!! Will get the turn down for it. Thanks for all the input!

[holeshot19]

i went threw tech at sundays gncc race and the guy said mine read 97 db the guys that went threw the line before me heard what the man said and we were all amazed but i had it as fast as it would run and all i can say is wow but it seems to pull everywere :blah:

[Phoenix78]

Originally posted by RobRacing
I got one on mine. It fit very nicely and there are really no cons except for the header gets discolored. I noticed a lot of gain on the bottom and mid but haven't been able to do a top end run. It is hella lound! Not sure how much louder than other pipes but it is definatly loud. But it sounds sweet. I just completly removed my air box lid. I am running the stock filter but am going to get a twin air here soon so I can dial in the jetting. Hope this helps.


Thanks for the info! Exactly what I wanted to know. :devil:

[2004TRX450R]

Good deal. That is the system I'm looking at too. I like the lifetime warranty they have. I've been talking with them to become a dealer for them but haven't gotten the details worked out yet.

[Got nads?]

Does it have a spark arrestor? Is it U.S forestry approved? Need to know for riding at St. Anthony sand dunes.:devil:

[holeshot19]

the turn down that bolts to the end of the pipe has a screne in it but you can add it or remove it

[900rracer]

I have the Duncan System I ordered straight from Duncan. I did not really ride my R stock (just up and down my street) then I tore it down and did the HRC kit, 185 main jet with the clip one down from the center, full Duncan exhaust, Tag bars, Ac bumper, grab bar, and pro peg nerfs, and holeshot MX tires front and rear with beadlocks on the rear. I rode the past weekend and loved it--it makes my 89 250R look stupid. I was doing 2nd gear stand up (standing in grab bar) wheelies on pavement on my 89 250R and lost it, stood it straight up and fell on the palms of my hands--took 6 stitches to hold my right palm back together! Anyway---I love the Duncan System--it sounds and performs great. I have pipe number 46 out of the first 50 they made