As far as boost guages go, there are some differences between styles and I would say it goes for other types of guages too. The increments are different a lot of times. Some only go up to 20psi and some up to 30psi. I've seen one with just boost and no vacuum readings. Decide what you want from the guage and then make sure the style you like has that.
Jonathan Howlett AIM-JRHZ32 1993 Ultra Red Twin Turbo 1990 Pearl Yellow Twin Turbo(Deceased)