Custom mapping IS better the REAL question is How much better. The maps you can download from the PC site are tailored to bikes with the listed mods. They likely aren't as aggressive as a custom map would be due to the fact that all stock bikes are not the same and all stock bikes aren't in the same location, ie elevation.
In order for you to reach your FULL potential you should have a custom map created for your specific bike under the conditions you are most likely to ride in. The Dynojet site offers maps that will work for general conditions, but all could benefit from tweaking for YOUR bike.
Make sense?
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