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Premium Member
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625 Posts
Discussion Starter #1
Whated to ask you people here because this place seems to know alot about the Fatcat.

I replaced my Rinehart Tru-duals with a Fatcat with quiet baffle on my 06 Roadglide. The fatcat pulls like a diesel from 2500 to about 3500 rpm and then feels like it really falls off from there. The Rineharts made 105 hp, 105 tq @14.5 AF but it was to high in the rpms. I still haven't had the PC tuned for the Fatcat but was wondering if anyone knew if the Fatcat had better top end performance than what I'm experiencing? I don't want to pay for a tune to only discover that I need to do something different to get the topend running better. I guess what I'm asking is does a Fatcat with quiet baffle have any top end performance?

My build consists of 95", 10.5:1 CR, 575 HQ cams, Hotshot head porting (www.hotshotmotorworks.com, Hotshot 50 MM TB, SE-AC, PCIII-USB, Rinehart tru-duals then but now a Fatcat with quiet baffle.

Thanks for any info.
 

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Average Dude
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6,263 Posts
I don't know much about the FatCat (but, I'd like to find out!). I have the RB Racing BlackHole which has plenty up top, but seems to fall short down low.
I know you can't have it both ways.
 

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Premium Member
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11,928 Posts
spin my 06 dyna to 7000 rpm, with fatcat. dyno shows tq falling before that for sure, but buttmeter feels the bike still pulling hard.
 

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<><
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3,971 Posts
The question's about the Fatcat -- YankeeBob contrasts with RB Black Hole. These are fixed, non-tunable exhausts. One gives more top end, the other more bottom.

I know some guys like the sound or looks of other pipes, but I had to go with a tunable (SuperTrapp) pipe. The fixed pipe is hit or miss to match your build.

After installing the ST (4th pipe on this bike!), I rode it with different numbers of discs. Spent a few days with each number of discs, and in the end, with my final 2 choices I ran it for weeks with each one so I could really catch the subtleties. It's absolutely evident to me that our bikes need an exhaust to MATCH. It just performs so much better. Good luck with your picks!

EDIT: My method was to bring the most torque into my riding zone. I added discs, reducing back pressure, running power up the RPM's. When it hit max power at redline, that was my max # (21 discs). I did the same on the bottom end side, subtracting discs until the power was as low (RPM) as it would go (16 discs). Top end was HORRIBLE. 17 still choked it too much up top. 20, power was too high & bottom end wasn't there. 18-19 was a VERY close call, but I opted for that extra little push up on top. :wootdnc:

You just can't tell what all your bike has, or how it feels with these subtle changes, unless you run a tunable exhaust. Too bad there's not a test mule exhaust to run with for a while, then pick a fixed of your choice to match the best choice backpressure.
 

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I have the FC on my 96 build, 37g cam, heads polished but not ported, flattop KB, DTT, etc. It pulls like a stump puller all the way up to where I wanna be. 80 mph = 3200 rpm 90 mph = 3800 rpm. acceleration after 90 is a little weak. I rarely go over 5000 even with aggressive acceleration.
 

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Premium Member
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625 Posts
Discussion Starter #7
I really hope it's just in the tuning. All the dyno sheets I see running a fatcat look like they still pull good all the way up the rpm. Mine on the other hand, if I crank on it, it doesn't seem accelerate to redline quick enough. At least not like it did with the tru-duals.
 

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665 Posts
I have to agree with SledMan. It may be the combination i have or the tune but if you could see the fuel/air mixture at all ranges of RPMs you would see that the fat Katz will do it all on both ends. It pull just as hard on the big end as the bottom end Booggerbe
 

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Premium Member
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625 Posts
Discussion Starter #9
I know now that it's in the tunig. I was playing around with the PC and got the top end back. You guy's are right about these fatcat's they're awesome. The only problem I have now is I have to pay for another tune for the PC3 if I want to be sure about hte AFR. I can't seem to leave things alone so I decided to get a TMAX instead of buying ANOTHER tune from someone I can't trust to get it right. I feel like it was a heck of a deal at 599.99 for the TMAX.
 

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HATER OF THE GRAVEL!!!!!!
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Just to add to the mix.....



I think I will keep my Pro pipe.
 
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