The Indy-Cator is a dream come true. It not only looks cool (well, don't put it in your dad's car, he might not think the same), but it really helps.
What's even more important, the Indy-Cator can be used with any manual transmission up to 6 gears, for any brand of car. There are some small issues (like you cannot use it for gear levers with reverse gear locking mechanism), but it makes no difference to me.
More, "a light sensor in the INDY-CATOR adapts the brightness of the digital display to the surrounding light by means of an automatic dimming function, ensuring optimum readability at all times". So much mambo-jambo. In short: the light will be as powerful as you need it, without creating any difficulties for you while driving.
Is it easy to install? Apparently so, since you have a full pdf manual explaining how to do it. So, go and buy it. You can find it here.