Hi Paul

Hope all is well ?

On stock 13 b s4 on both primiere and secondary fuel rails you have
fuel pressure regulators are both rated the same pressure and will it
be possible for me to remove both regulators and run a single one
adjustable regulator on the line that feeds back to the fuel tank ?

Cheers
Barend

Yes. That is what most people do.

BTW That makes me think somebody should record the fuel pressure
1000 times a second with a data acq system. There may be something
going on there we should know about.

Paul Lamar