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Discussion Starter #1
Okay, I have a 2004 750 Brutale running on standard (as far as I am aware) ECU and chip. Following a chance purchase of link pipe and arrow silencers, I fitted them to the bike removing the standard (but gorgeous) silencers and the cat/collector box.



The crackle from the arrows was quite impressive and after a few runs I noted that although the bike initially seemed more responsive above 6K, it would occasionally cut out as I dropped the revs when approaching junctions. It also felt a increasingly woolly between 2-5 K revs. In fact it got to the point where I though I'm going to put the standard silencers back on

As I was using the bike for work yesterday and would be heading out early I dropped in the DB killers that came with the silencers (I like my neighbours) . On the run into work, it felt like a different bike. Okay more muted but it felt smoother, the woolliness had disappeared and no cutting out when coming off the revs. Just to be sure I took it out again today for about 80 miles and it definitely performs better with the DB killers in

Is it possible that the open silencers upset the fuelling?? I know with my T509 Speed Triple I have to alter the map to suit whichever silencer I am running and the bike is incredibly sensitive to the issue.

Anybody else experienced this??
 

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Open silencers usually will make the motor lean out. If your too lean, it's possible to melt a piston or two. So I'd be careful in your case. I'm not sure by what you mean by the bike acting "Woolley", but a lean motor has too crisp of a throttle response, better gas mileage and could run hot.
 

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Bottom line is...YES.....the open pipes require different ECU mapping. The dB killers essentially put the pipes back close to stock in performance (lighter and sounds a bit better, some would say looks better).

Contrary to popular belief, sometimes open pipes will actually make a bike run more rich. There is a lot more to exhaust system design then sound.
 

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Also Back pressure is effected,Fueling will be out by miles.Some people live with it,I cant ,I actually have mine Dyno tuned once a year.so I know my fuel mixture is correct.

cheers eddy
 

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Discussion Starter #5
Thanks all for the quick responses, you have confirmed my suspicions, I'll leave the DB killers in as I also like the sound with them fitted.
I have a microtec ECU which I want fitted in the near future so I'll be getting the bike dyno'd at that point anyway.

Are the free-flow air filters that I see advertised eg DNA, BMC, worth the money??
 

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Thanks all for the quick responses, you have confirmed my suspicions, I'll leave the DB killers in as I also like the sound with them fitted.
I have a microtec ECU which I want fitted in the near future so I'll be getting the bike dyno'd at that point anyway.

Are the free-flow air filters that I see advertised eg DNA, BMC, worth the money??
Definitely. I had a BMC one fitted and when Chris installed and set up the Microtec he couldn't get it as he wanted. There was a slight dip in the mid-range no matter what he tried.

He tried an MWR filter instead and it lifted the mid-range up perfectly.

Obviously every bike is different with unique set ups so probably worth discussing with your Dyno guy first.
 
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