R6 muffler/cat

[Jashdown]

I'm thinking of getting a link pipe for the r6 and chopping off the muffler box. Mainly for some better sound and the marginal power improvement. I'm just wondering if leaving the cat in the headers will have much affect on the volume and also the power.

Reason I ask is because I can get a full system with the link pipe already welded on, with the slipon included for a real cheap price, but the cat hasn't been drilled out.

If there is that much difference between cat and no cat, I'll just buy a link pipe and cut my own exhaust and drill out the cat.

[Marshy]

No difference, or if anything the bike runs slightly better with the cat in. Don't cut/drill it out.


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[Jashdown]

Interesting. I would have thought the cat would restrict the flow a fair bit and soften the noise. But I guess unless you're trying to get every last bit of power out of the engine, it won't make much difference.

Are they noticibly louder with the muffler cut out?

[Marshy]

Probably.

But people always forget that back-pressure is vital to performance in normally aspirated engines. Without back pressure they lose a touch of top-end power and a LOT of midrange. Obviously too much back pressure will strangle the breathing too, but not enough is also bad.

The latest fad of SC Project/Austin Racing style of open pipe looks and sounds awesome, but actually hurts performance. There's a reason that Akropovic race cans are not little trumpets.....


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[Mr.Ed]

Except on the zx6r where the cat has a tendency to collapse and block gas flow... Full system sorted that though

[Jashdown]

Good point.

Another question while on this topic. If I remove the muffler box and hence the majority of the restriction, will I need a power commander or bazzaz fueling unit to increase the fueling since it will be running leaner? Or should it be alright to run as is for a while and get a PC/bazzaz at a later date?

[Marshy]

It will help a lot, but you won't blow up the motor in the meantime. You'll lose a bit of midrange until the fuelling is fixed....

[Turbo]

It will help a lot, but you won't blow up the motor in the meantime. You'll lose a bit of midrange until the fuelling is fixed....

Yep, mid-range will feel a bit lumpy. I was adding up to 30% more fuel in some spots, on the dyno, to get it smoothed out after lopping off the collector.
Keep us posted! :thumb: