Im running a 97 Ex 5speed, bolt ons are Megan 4-2-1 header, AEM SRI, WS2 exhaust system. Im interested in changing my cams but I dont know which ones to get adjustable or racing and what stage should I be looking for. Also what exactly is valve train, is it replacing the stock springs and valves with performace springs and valves. What exactly is porting and how much should be done. Im trying to improve my engine with upgrades no nos or turbo.