I have never really been happy with gas grills. It seems some cook too
hot and others do not get hot enough. I have had this old Sams
stainless grill for years and the ability to slow cook something like
chicken is great but if you want a quick steak, it needs more heat.
I decided the trick might be to play with the gas pressure. I have had
a few regulators on this with mixed results so I went with an
adjustable one. That gave me great control of the fire, up to the
point where the flame was coming out the top of the grates. The
industry standard for a "gas grill" bottle regulator is 11" of water.
Using that as a bench mark I went through my junk and came up with a
0-25" gauge. It turns out these bottle regulators suck. I tried 2 of
the 3 I had handy and they do not regulate well and the flow
restriction means if you have all 3 burners going, you might only get
7-8" of pressure. It is really all over the place. I also found out a
little dab will do ya. At the true 11", the burners are pretty hot and
at 15-16 they are really going. I did some steaks tonight playing with
the burner valve and the pressure. I really started feeling like I had
some control of the heat. It seems like far more control than I got
using the burner valve alone. Part of that is the pressure was not
that stable with the original fixed regulators. Now I am going to
start correlating what pressure is optimal with what I am doing.
I would not recommend an adjustable regulator if you do not have a
gauge unless you really like futzing with stuff. I may be looking with
one that is more precise and less range. This thing goes up to 20 PSI
(well over 100" of water) which might be OK for a turkey cooker or a
moonshine still but not useful with a grill.

http://gfretwell.com/ftp/Grille%20Guage.jpg