what is the difference

[navmk4gti]

im looking to get a turbo gauge for my mk4... but i come accross 2 types.. a vacum gauge and a normal type.. whats the diff?? i want the one which actually measures my boost in PSI on throttle and idle... and bounces and stuff.. iv seen them they look wikid when there bouncing  but im now confused which one i need 

[topher]

got links for the ones you're looking at?

there will be vacuum at idle, which some boost gauges measure aswell as positive pressure... other gauges just start at 0 psi/bar

[navmk4gti]

yh heres the link http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=200375979750&ssPageName=STRK:MEWAX:IT

let me know if it will work says it is a vacuum one...

[topher]

yeah that's just a vacuum gauge by the looks of it, so when you're on boost it'll read 0 (unless you plumb it before the turbo.. but then you still won't get an accurate reading)

if you look at this one

http://cgi.ebay.co.uk/New-in-box-52mm-Turbo-boost-car-gauge-psi_W0QQitemZ150366920234QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2302911e2a&_trksid=p3286.c0.m14

you'll notice it will measure both the vacuum at idle (in Hg) and boost when on song (psi) .. most boost gauges use this method, but there are some that don't measure the vac at all and just start at 0 psi or bar

[navmk4gti]

so i need one which reads both to get a better reading?? 

[topher]

you don't necessarily NEED it.. but that would be my recommendation

[navmk4gti]

yep i think im gonna go for one with psi and Hg.. thanks toph 

ill post what i ordered once i make my mind on which one