Join Date: Sep 2011
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The R3 is going to be a much different bike from the CBR. You are going to need to spin it a lot higher to get to the power.
Altitude does reduce power (less air = less power) but if you like most everything about the CBR250R the CBR300R would probably feel about the same given the altitude change. Most likely it would still feel stronger than the 250 did.
I'd personally go for a Ninja 300 or 400 over the R3, but the CBR is still going to be stronger down low - if that's what you like.