I am not sure about boost gauge being standard on the STi, but I am pretty sure you can get it as a factory option.

 

yup..

but they so badly placed.

i ll never ever get them..

they are on the center control panel.. all the way at the bottom..

below AC below space for radio .....


last place i ll look at 100mph..


even the stock boost gauge is badly placed..

so tiny too..

 

I wouldn't worry about voiding your warranty with a boost gauge. Most delaerships should understand the importance of a boost gauge. It's only a T off a vaccuum line, i.e. the fuel pressure regulator line.