Adjustable cam gears

What gains would I get with factory cams and cam gears. and with a 91 nissan intake cam and cam gears . And how do you adjust them. is a dyno required or will a g-tech work. I know that it would be better to get aftermarket cams but I'm not looking to be the fastest just a little faster and not broke

No ones really experimented with cam gears on the stock cams. Dyno would be the best bet. However you need to remove the valve cover to change the cam timing so it's a real PITA.