Yeah I know what you mean, they can be pretty noticeable where I got them now. The glowshift one my mate has about 8 colours available which is nice to mix it up a bit. When you do get a gauge just mount it temporarily (so you can decide on the best place) on the dash, on the side, another option is just on top of the steering column where my mates 52mm gauge is. That way you can't really see it when people look in through your window, and its also near your instrument cluster. You may also want to consider a gauge hat as shown in my pics. It should help daytime viewing and I think it looks a little more finished.
This is a thread of the guy I got the gauges from. A different angle to where he mounted his gauges (similar to me)
I'm looking at mounting my Prosport boost guage on the flat surface behind the steering wheel on top of the steering column so it sits effectively between the two main instruments from my viewpoint. This keeps it low and out of the sun, away from prying eyes and more importantly away from the side-pillar airbags. Last thing you want after a full-frontal prang is to have to tweeze a boost guage out of your forehead after it has been driven into it at 200kmh by the pyrotechnics. The lighting colour matches the instrument red, which I greatly prefer, being long wavelength and it is better for preserving night vision than all the chintzy short wavelength blues one tends to see around.
Due to the serious shortage of wiring ports and useable grommets through the MPS6 firewall, I have found a location where I have been able to create a new 25mm diameter port with a chassis punch, into which I have inserted a rubber grommet to cut out noise, fumes and smells and prevent cable chafe, and that enables me to duct all new instrument wiring through one place and still enable fair access if I need to pull it out or add more. I then run spiral wrap around my cabling on both sides of the grommet so it's nice and tidy, then cable tie it up out of the way. There aren't many easily accessible sites that are high and weatherproof and enable one to get a drill in for the starter hole for the chassis punch. These cut a nice neat round hole.
I think my next task will be to take a leaf out of my boat design (boats are all dual cabled as they need +ve and -ve cables from everything, so have live busbar boxes and a common earth busbar placed near instrument consoles) and set up a single covered and (high-amperage) fused "hot point" busbar, so those cables that need to be "connected direct to battery" are in fact taken from the busbar and are also independently in-line fused. This saves all that poking around under places like the gear-shift console and other weird places that I see folks doing to take power off the back of accessories such as the cigarette lighter, etc. The earth is easier with a car than a boat as it only requires a nearby body metal mount. And once set up it's all way safer than hot wires coming off every nearby wire, saves potential for shorts and leakage and inadvertent power drains, and there is only one required point of inspection and access.
CP_e Standback & PNP; CP_e 3" SS Downpipe; Corksport FMIC with Top-mount K&N filter & OEM Ram CAI; Turbosmart BOV;Dashhawk;Prosport Boost Guage;Sumitomo HTRZIII's in 225/45 x 18