I stand by autometer, they have good quality and have alot of diff styles to suit you or your car. They are fairly pricy, but you want a good one. I got a 30psi autometer phantom guage on ebay for like 65 cdn or sumtin after shippin and stuff.
As far as should you get a turbo timer, you dont need one thats for sure. But they are nice little things to have, most likely have a longer living turbo, because then you cant forget to let the car idle after hard ride. Also people think your car is the craziest car when they walk by and it turns off on its own.
Id say you should get a turbo timer, but others think its a waste of money. I personally didn't like sittin in the car and waitin, you look kinda dumb sometimes too.