So I did a quick search and found some dated threads on people punching out the cats from the stock headers of 09-12 zx6rs. Mostly how-to's. Seems pretty straight forward and can be done with headers still on the bike. Drill out multiple holes until most of it comes out and scrape off the residual honey combs / dust.
What I'm really interested in is what gains / drawbacks does this create? I have an FMF Apex exhaust with the "boom-box" or pre-muffler removed so this would essentially create a "full exhaust."
Obviously this would require a power commander or a remapping. Has anyone done this and if so:
1) Does this create the same performance gains as you get from full race headers?
2) Could there be performance loss due to lack of back pressure even after re-mapping?
3) Also heard that the cats sit in a small expansion chamber which when cleared, reduce flow through the headers??
4) How does this sound versus leaving the cats in?
Hope to get some real facts on the mod, so thanks in advance for the contributions!!
I have done this, I ran a similar set up to you and had good results so I will try to answer your questions.
1) You will get similar performance gains but not the same, most gain about 9hp with gutted header which is on par with most full sytems give or take 1-3 hp. A full system should gain more in the higher revs while gutted stock header might be a little stronger in the mid range. The true advantage of gutting your header is the money saved vs a full system, I spent 225 on a slip on and you can gut the header for free as opposed to 750-1700+ on a full system.
2) I did not see a performance loss anywhere after tuning, don't know why you think you would that. A proper tuner will tune to gain performance... In fact my bike ran cooler as well.
3) I never heard that and that makes no sense to me, when looking at this pic of my stock header gutted. The whole point of clearing it out would be to increase the flow.
4) Sounds about the same to me maybe a little deeper, I couldn't really hear a difference.
Here's my dyno chart so you can see the power curve etc, (sorry it's sideways) pretty straight and smooth and good power gains through the whole rev range, seems like a win win to me
DUA Motorsports Bodywork, Akrapovic Moto2 exhaust w/ Akrapovic SS full system, Attack Rearsets, Bazzaz ZFI TC, Kawasaki Kit ECU, MWR race filter, Fren Tubo type 4 carbon fiber brake lines, Braketech Iron Axis rotors, , carbon Fiber clip on tubes, Renthal clip ons, ram air mod, Attack velocity stacks, Motion Pro quick turn throttle, Brembo 19x18 MC, custom carbon fiber subframe, Ohlins TTX36, Ohlins 30mm cartridge kit http://zx6r.com/pictures/26715-my-09-track-bike.html