To tell you the truth....before i wrecked my car...i researched all the engines i could get for it...which basically were the D B and H series... *K was too expensive...anyways*
Each series has its own pros and cons. It all depends on what you want, when you want it,how long your willing to wait, how much cash, and how your going to get to it. While researching everything i would need to get the engine and my car where i wanted it, i need to build it on a system of some sort. Like if you get an intake, you have to get an exhaust system. If you get cams, you might as well match it up with the right internals. Engines should be built on a system thats planned to build upon itself and work with other components in the engine to put max effiency and power to the engine.