Yep, you need to.
The K&N on its own would not need it, but the Full race system sure does.
This totally changes the exhaust flow, which affects how the bike runs.
If you don't, it won't run right and can damage the engine over time.
It might help, but you really should rejet. If your putting all that money in to a bike, better do it right or dont do it at all. I would suggest investing in some dyno time aswell.
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