Jetting with the Big Gun

Just took delivery of the Big Gun Race Series header and silencer today. I'm putting it on my '99 WR400 with WR timing, grey wire cut, air box lid off, and throttle stop cut. I ride mostly in Florida near sea level in hot weather.

I'm looking for guidance with jetting. In general, do I need to go richer or leaner than stock? From what I've read so far, I'm expecting to modify main jet, needle, and pilot jet as needed. Do I tune one at a time? Which one first, second, etc.?

By the way, my bike runs great now with stock exhaust. Just had to try the Big Gun.

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