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Cat Converter Removal

I built a 2 in 1 exhaust for my 1100. I attached a muffler from a 1300 and removed the cat converter. I attached the muffler to a bench, hooked up a 1 1/2" dia hole saw attached to a 12" extension on a 3/4" drill and chewed it out completly. It was a bitch to get out. My bike has carbs, so I had to perform some adjustments on the PMS and re-synch. The muffler does not appear to be all that efficent. If you are looking for a HP boost you will not find much. If you are looking for a better sound, I think there still isn't much advantage. If I were to do it over I'd buy a performance pipe.

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No. Some amount of back pressure is needed to allow for exhaust scavaging. If you remove tha baffle you have a straight pipe, this will reduce your HP at the 0-3/4 throttle range.
 

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Discussion Starter #6
Do the Cobra Slip-on's offer any resistance (back pressure)? I also thought about that option, but I already have the stock pipe (obviously), and if I can make that work instead, I would just go that route and spend the money on something else. Also, doesn't the 2 into 1 y-pipe offer some back pressure in and of itself?

I'm not necessarily looking for a truckload more power, but I'd be ok if it did have a bit more. I'm more interested in getting rid of the stuffy VW bug sound coming from the pipe. I have a K&N filter that came with some other parts I bought, and it seems a shame to not use it to it's full potential.
 

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There is not a top fuel or a drag racer that would agree that you need back pressure. Back pressure is a bad thing that is the reason we add free-er flowing exhaust.

http://www.gomog.com/allmorgan/exhaustbackpressure.html
Yeah that's great if your going to run alcohol and rev the engine at 8000 for 1/4 mile. Sucks if you want to stop and go at part throttle. However the issue isn't back pressure its velocity vs flow. Open pipes make for slow air flow and poor scavenging especially at low rpm. The exhaust gasses actually sit in the pipe. However obstructions aren't good either. Best power is a smaller 2 into 1 pipe. Just doesn't sound cool. Baffles do effectively reduce inner diameter just not the beat way to do it. But the increase in diameter does change the flow rate which is why the fuel and air mix must be adjusted and in some cases the timing. The back pressure myth has the right idea it basically an issue of semantics.


Edit. Hey I just checked that link and it basically says what I just said. Good link.
 

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Well to put it simply when you get to high rpm the exhaust pulse is so fast that the effect of smaller pipes becomes irrelevant. Notice that these cars have little power at low rpm. ( formula 1 , top fuel etc )
 
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