i searched this and couldnt exactly find what i was wantin to no. Is it ok to run without the stock muffler i no it helps with back pressure but what problem is that gonna cause. i personallay like how it sounds wth straight headers. u dont have to tell me thats its illegal or that i might lose some acceleration i just wanna no if its gonna hurt my engine.

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THe peak rpm range wont be attained, but it also will not hurt the motor. Plus it sounds sick. Get a six inch two brothers pipe definitely the best pipe for a cbr...