Audiophobe, sorry I missed your point

This thread started as questions on 3SX/ lighten pulleys, which I also have questions on. If you want to address the group buy on DOHC headers, why don't you take it to that thread?
Personally I learn by researching (many hours of text book work and internet searches), asking questions of the design engineers and experienced users (racer car drivers and race organization staffers) that have been down the path before and lastly, first hand observations and data taking with the tools on hand( over 35 years worth of hands on).
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'91 Stealth RT, DOHC, NA; many mods
'93 Stealth TT, Stock