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Has anyone managed to remove the stock muffler insert/ restrictor on '12 model?

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Hey Folks. 

I have a '12 model RMZ250 with full SS Yoshi system on it. Seeing Yoshi's dyno chart doesn't (attached) give me much love for the RS-4, coupled with it's increase in weight.


I was wondering if anyone has managed to find a way to remove the cylinder shaped restrictor insert in the standard muffler core, and if so what was the effect on noise level, and power? And most importantly - How did you remove it?! 


I run my RS4 with the spark arrestor in, for better mid range, and the lean fuel map connector, for more grunt as well. 
I'm a mid rpm rider, I never peak my motor out, I'm no Tomac by any means, just a Vet recreational rider. 

However I do have a 270 kit on it's way (for more grunt again) which I'll run on rich coupler. I feel that a derestricted stock muffler would allow plenty of airflow for it. 


Alternatively, does anyone run a 270 on a full stock ex. system, and if so how does that go? I really want my power in the 7-10,000 RPM range. I'd rather pull wheelies than holeshots, so I dare say I dont even need full open flow. 


I just think I'd be better off flogging the RS4 to fund some cams or a programmable piggyback (PIM2/ PCV)

Any feedback is appreciated. 

Certainly when I get my 270 installed I'll be trying some comparisons of my own. 



Edited by brenno

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