Stephen,
With both of my old MC18`s, I ran 185/182 mains with JHA pipes, and modded airbox.
To get the full advantage of aftermarket pipes, the emultion tubes, MJ needles, and pilot jets should be changed as well as the air soliniods blocked off. The whole purpose of the air soliniods are to create an over-rich condition at 10,500 rpm by bleeding off the air flow to the emultion tubes (the dyno sheet should show when the soliniods activate).
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Mike