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Discussion Starter #1
Hi,

I have read a couple of the how to threads on this subject and I am wondering if when you open up the canister and install the 2" straight thru baffles, if there would be any benefit at all whether sound wise or equalization of the exhaust to connecting the 2 baffles with another piece of pipe making it into an H pipe like they use on cars?

There has also been talk of the raspiness that comes with making this modification, would it not sound better if you simply removed the Cat from the canister and replaced it with another piece of pipe, this way not changing the internal workings of the exhaust, simply removing the cats ( also the other one in the Bottom pipe) .

Lastly there has been mention that in order for it to sound good and get rid of the raspiness that I talk about, there should be a size difference from the diameter of the internal baffles to the exit pipe. Should the internal baffle br larger than the exiting pipe and then what if that H pipe is added?

Thanks for any input, I want to make this mod to get rid of the heat associated with the Cats while at the same time making the bike hopefully sound better, I had carbon Leo Vinces on my Monster which sounded incredible and this stock exhaust just isn't cutting it!

I fo have a power commander and as such not worried about the outcome as icanhave bike dynoed and adjusted.
 

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Greetings from Coquitlam Ducoudakis!

I cored the exhaust on my 999 using 2'' stainless perforate piping I picked up online. I didn't experiment with an H pipe, but honestly, it's pretty tight in there.

Also, sure, sound is subjective, but I thought it sounded indistinguishable from the real termi. I found the sound settled a lot too, after maybe 500k, I didn't hear even a hint of rasp after that and you could really rev the thing. The bike was loud, but not obnoxious, not as big of a step up in sound as throwing a shorty can on a 600, for comparison. Damn, I sold the 999 last year, but I miss the bike to this day :).

By the way, when I was coring my exhaust I picked up 2 spare duc mufflers but ended up coring only one. Shoot me a PM if you want to pick up the other one, can keep your stocker for resale.
 

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I have a cored xx9 system I could sell "exchange"if your interested ,I"m in nanaimo
 

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wouldn't bother with the H pipe. pretty sure the exhaust merges to one pipe after the headers then splits to 2 again (well they do on a 996 etc, just can't remember if they do on the 999 for sure) so the gasses have already merged.

and don't remove just the cat. the whole mouse maze in there is what's restrictive too. gut it all and fit the straight through perforated pipe and it'll be lovely. someone just posted some great pics etc on here a few days ago.
 

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On the 749 there is one cat in the piping, and the other is in the exhaust as well, so removing just one is going to be troublesome. In my opinion if you are going to core the exhaust and removing the cat, you need to remove the other. The other cat should be in the horizontal pipe. Once you do that then I would core. I would do an "x" style or "h" style, not for sound (even though it would be cool), but because it would cause that necessary back pressure. I have a full termi exhaust right now and it removed both cats. You could take your OEM horizontal pipe an remove the cat cheaper than a new pipe. Also, what year i your 749, and is it an "S"?
 

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Discussion Starter #6
Hi Guys,

Thanks for your input.

If I do this I will definitely take out both Cats, not just 1.

Have never done this before and wanted some info from guys that have . Everyone is telling me that the cored exhaust for this bike sounds great which is very encouraging as I have heard some on other bikes that in my opinion did not sound so hot. The other big issue is to also cut down the heat on the boys , even though I have had kids , still not a pleasant feeling when things get that hot down there.

Pomo and Kaos , can you please Pm me with price that you are wanting for the exhausts, that will give me 2 options (thanks a lot!!) .

Once again , thanks to all for reading and replying!!
 

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Discussion Starter #7
One thing that I forgot to mention is that my 749 is a 2006 , not an S model.
Please let me know if the exhausts that Pomo and Kaos have would fit.

Thanks
 

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what is the purpose in the perferated pipe? would you need the perferated pipe if you were planning on doing the "H or X" style for the back pressure?
 

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what is the purpose in the perferated pipe? would you need the perferated pipe if you were planning on doing the "H or X" style for the back pressure?
To get rid of the raspiness and make it not a straight through exhaust basically.

Check out my blog or my thread, I'm doing exactly what you are planning right now. Learn from my mistakes before you try it :D
 

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I have a little insight with the whole coring exhaust............

I have a 749 in with a really botched up coring job. It didn't have the perforated pipe or any way to connecting the two cylinders together. (On the 9 series bikes the exhaust merge inside the can.) This caused the bike to be entirely way too loud (subjective, I like a good rumble but if you want a race bike....... keep the license plate off it.)

If your not interested in hunting down a Termi slip-on, I would do an X pattern in the rear can with 30 degree 10in bends out of two inch pipe. I would perforate them because the point of the perforation in the Termi desgin is to help with Cylinder signal. So instead of a very difficult and complicated X pipe Termi went with the open chamber with perforated tubing.

The basically straight pipes that this client bike has made it run rough and not to the riders likeing. After removing the can and replacing it with the stock one we found a lot better performance. Now I will say this.........

I am a little confused on where the second Catalytic converter hides. I know the pipe coming from the horizontal cylinder has one just behind the engine before the pipe turns to go up to the Cans. But i'm afraid i don't know where the one for the vertical one is? There isn't much pipe there to even have one. Not saying anyone is wrong I just want to know.

To recap........ unless you know someone who is a damn good fabricator........ save your pennies and get an aftermarket can.
 

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Here's a image from my coring thread showing the cat location in the rear box

 

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Discussion Starter #12
Update

So, I have now successfully gutted the stock 999 Can that I picked up which is exactly the same as my 749 (FYI) (still have my stock one to fall back on , should the cored one be excessively loud or sound like crap). I was going to order the LA Chopppers baffles online , however was getting jerked around as to when they were going to be shipped and decided to have the guy that is doing all the welding for me to make them for me. He takes flat perforated stainless stock , rolls it and then welds it to whatever diameter that you need. I have found out that part of the problem with doing this modification is that once you repack the can with fibreglass packing it will over time get blown out and the bike will gradually get a lot louder. SO , what I decided to do was that once I opened the can up I kept all that stainless steel packing that is in there (both from the top and bottom) and am going to wrap it around the baffles and secure it with stainless wire , then I am going to pack it with the fibreglass. In this way I am hoping that the stainless will actually act almost like a filter not allowing or slowing down the rate at which the fibreglass will get blown out thus increasing the life of the can. Certainly want to avoid having to cut this open to repack it again . I have purchased FMF 4 stroke packing as was told it was the best to use.
Secondly, the guy doing this work for me is going to cut out the cat from the bottom pipe and re-weld a stainless pipe in its absence thus eliminating both cats.

If anyone is here in the Vancouver/ Lower mainland area and is looking for a guy to do this work , the guy that I have found I am realizing is the Guru for this type of work . In the 20 mins that I was there dropping off my stuff , 5 guys showed up dropping off similar work . I will post his number for anyone interested (its in my car outside right now and Im sitting at my computer first thing in the am sipping my coffee, not getting up).

Will let you know how this turns out and hopefully will post some pictures as he is going to take pictures of the progress so that I can see what he has done to it prior to welding it back up.
 

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Discussion Starter #14
So , Its all done and installed !!

Sounds fantastic, now its a matter of tuning the bike to run properly with it.

The only down side to the whole thing and I think that its entirely possible that I got screwed, but, the guy that did the work for me charged me $500 , ouch! Thats for getting the peforated stock , rolling it into 2" baffles, instaling it, packing & welding it closed, as well as removing the cat from the front pipe . I took the muffler to him fully gutted ready to go, he said that just to weld it back together took him 2 1/2 hours, which I find a bit hard to believe , but, he did do a good job. All in all the whole thing cost me close to $700 I figure, then I come onto the forum today and notice that a guye sold a Termignoni with the catless bottom pipe for $995 ?!?!

Such is life I guess!!
 
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