I would think one could do the same as we do on the intake when the boss is removed and the cap/pipe plug is installed .(Drilled&tap) and blended flush with the top of the port. And not have to worry about doing any welding to the head for those That can not weld Or have someone else do it. And also this avoid any chance of the head warping. Just a little more food for thought on this matter. I had a whislte at one time But it was coming from the carb. Rebuilt it and that was gone I never did figure out what made it do that But Oh well water under the bridge LOL. }[oooooo]
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NovaMan/Twisted6/Larry