There is many different things I could rate as #1 mods before fucking around with this on the internet advice of others.
That's just me though.
Calling this #1 reliability mod is so off base its not even funny, not to make a point Barry but it just is.
Put in a proper cooling system
Put in a proper thermostat
Put in proper drive pulleys
Tune your car right
Run the right parts on a rebuild
Find a legitimate rebuilder (#1 best bit of advice)
Find a rebuilder who has a running car to show what he preaches lol
Run a proper ignition system
Tune the car correctly
If its turbocharged make sure its water injected (absolute #1 reliability mod)
Don't use after market apex seals (#2 reliability mod)
Don't go to BDC for anything (#1 reliability mod)
Don't read anthying written by Howard Coleman (#1 reliability mod)
Use the internet mostly for porn (#1 reliability mod)
I've never had "carbon wings" LOL like I stated, some do, you have to question why???? probably cause they don't do any of the other basics properly???? Mis diagnosis and false conclusions abound........ welcome to forum hypothesis