The evo which i bought doesn't have any auto gauges installed, which ones are necessary/worth buying (oil temp/boost/turbo etc)? Thanks

 

none are necessary or needed. people buy them because they want the look of them or want to actively monitor what the car is doing. boost, oil pressure, oil temp, wideband are the most popular / most useful

 

On a stock Evo which I assume yours is it's not necessary. Some people install them for looks and other when starting to really modify substantially as they're functional. Personally unless I need them I wouldn't install them, I live a clean look. I know others love that "gauges, racey, the fast and the furious" look but it's up to you.