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Getting the cat out of a Fat Bob exhaust

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Old 04-01-2011, 03:47 PM
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Default Getting the cat out of a Fat Bob exhaust

I've been wanting to get the restrictive catalytic converter out of the stock headers on my Fat Bob for some time but never quite wanted to butcher them cos they cost 550 to replace if I **** it up.

Then I saw some used '08 Fat Bob headers for sale on eBay and these aren't supposed to have a cat in them. I bought them for about 75 incl P&P and that's a bloody great bargain considering when they arrived they looked like new.

Trouble is that these have a cat in them too! Damn the Internet and its unreliable opinions. At least I have some headers without the dumb UK-model valve in them.

Anyway, now I have a spare set of headers that I don't mind butchering. The cat sits in the 6" middle section of the 2-1-2 and I need to get in their and scoop out the cat.

Anyone done this or something similar?





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Old 04-01-2011, 03:59 PM
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I have heard others say the early ones don't, but I believe all the Tommy Gun style pipes have them.
I bought a set of 08's to mod for mine as well, and yes they had the cat. The only way I can see to remove the cat is by cutting them. If you cut them right where they split back out to 2 pipes, you can use a hole saw to remove the cat, goes pretty quickly, just cut and dump as you go.
You can see a little more in the link below my sig pic.
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Old 04-01-2011, 04:11 PM
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i thought the older models didnt have the cat. i learned something here, again. i saw a post some time ago that someone cut the cat in 1/2, cleaned it out and just reweleded backtogether.
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Old 04-01-2011, 04:15 PM
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Originally Posted by pontiac69 View Post
i thought the older models didnt have the cat. i learned something here, again. i saw a post some time ago that someone cut the cat in 1/2, cleaned it out and just reweleded backtogether.

Yeah, if I was going to just reweld back to stock config, I would cut in the middle of the collector so you could weld a piece of strap over it just to strengthen it.
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Old 04-01-2011, 04:40 PM
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Not to derail the discussion, but has anyone tested the stock pipe with and without the cat to see how much power it robs? I say this because for years everyone was quick to cut the restrictive cats off our Camaros, Mustangs, etc, to let them breathe, but the new designs are way more efficient and don't really show an appreciable difference with or without them. It just seems like a lot of work to cut and weld if we're only talking 2 hp or so. Of course, the units on cars may be very different so who knows?
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Old 04-01-2011, 04:43 PM
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While the extra power is nice, I think the biggest difference comes in the sound. I cut mine out because I didn't need it on an 05, and just because I could.
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Old 04-01-2011, 04:46 PM
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".... i thought the older models didnt have the cat."

I purchased an '09 F-Bob header off ebay that was definitely flow-thru, no cat, and it was a direct-fit for my '010 F-Bob.
Kinda strange that an '08 header would have the cat in it.....
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Old 04-01-2011, 04:53 PM
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take a broom stick and shove it in there....hammer the end of it youll break the honey comb up and then you can probably sell the stuff to a scrap man because there is precious metals in the converters insides...
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Old 04-01-2011, 04:56 PM
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take a broom stick and shove it in there....hammer the end of it youll break the honey comb up and then you can probably sell the stuff to a scrap man because there is precious metals in the converters insides...
Good luck with that, it isn't that soft or easy. I tried drilling first, but it only removed what was actually drilled, the rest stayed intact, then I tried the holesaw, that made it easy.
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Old 04-01-2011, 04:58 PM
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i think it really depends on where the bike is sold. i know for a fact that california, and similar emissions states require more than others. for example. i live in valdosta ga, no emissions laws, but in atl there is and anything 96 and up must pass the sniffer. i think that could equate to the diffrence. im just going to cut open, gut and re weld the case. i did it on several car mufflers so im not affrid to do it on a bike. im only worried about bakc pressure and such, but there are baffles for this too .
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212, bob, catalytic, cats, converter, exhaust, fat, gun, hd, head, pipe, pipes, removing, tommy, yeah

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