I have a b17 stock engine, i was wondering if I just change the cam gear for an AEM or any other brand, would I notice any improvement? it is worth it?
You’re not going to notice any difference if you keep the same settings. The purpose of adjustable cam gears is to advance/retard the opening, and therefore colsing, of your valves. However, aftermarket cam gears are a nice cosmetic upgrade.
That’s my two cents. If it’s innaccurate, somebody please chime in and enlighten me!
True, timing gears on their own are not power adders. It is the tuning adjustments that make the power. But they do look nice, especially with an open cover. Would this be considered a repost, lol, sorry. 
the valve cover needs to be cut for the gears right? or the timing belt cover be left off to show off the gears? the gears will allow timing adjustments on the stock came which can net results at in Hp gains but with the stock cams its either gonna gain up high and lose down low or visa versa
The valve cover doesn’t need to be cut to fit the gears, they’re the same size as the stock ones. It’s aesthetically pleasing to see some shiny new adj. cam gears in motion though. A lot of people cut away like 6 inches of their timing belt cover too.