Originally Posted by Scootah
IIRC keeps flapper open all the time
Yes it does keep it open all the time...
but above 3k rpm, golf tee mod or not, the flap will open itself
OEM spec: cold start or not, the flap is always closed
under 3k rpm. Opens naturally above 3k.
Golf tee mod: forces flap open all the time. Hence cold starts become quite loud.