It should never go into the red, unless you've fiddled with it. Cars
made past '86 don't have red anyway, just yellow and in those full boost
is about halfway into the yellow. You really need to hook up a
calibrated gauge to have any useful information, no need to leave it
installed, just tee it in and go for a drive, then you'll have an idea
of what the needle position on the factory gauge represents.
