If you really want to get the engine running right with the new exhaust you will need a piggyback fuel controller.
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Bazzaz for Suzuki Burgman
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And a dyno session to tune the mixture at the tail pipe. Or the additional wide band O2 sensor mixture mapper.
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Accessories : Z-AFM Accessories
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Maximum fuel economy looks like you will want to set the weights to cruise at (or below) 5,000 rpm. Maximum acceleration and horsepower peak is from 7,000 to red line but I can't really see needing to tune the pulling rpm's that high with 40 hp on tap.