I have FD1 Honda Civic (1.8L SOHC iVTEC), what's the best upgrade to do to gain power? Have the cam ground? Already has a Mugen Exhaust?

I have FD1 Honda Civic (1.8L SOHC iVTEC), what's the best upgrade to do to gain power? Have the cam ground? Already has a Mugen Exhaust?

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