I have a 5-speed 06 Mazda 3 with the 2.0L engine. It's making a terrible knocking noise but doesn't sound as fast as a rod knock according to someone I talked to, who mentioned some magic loose bolt somewhere he couldn't elaborate on. Anyway, it's a loud engine knock, and loss in power. I'm going to either tear down and repair or rebuild the engine, or just do a swap if it isn't too difficult. What swap options do I have and what's involved in them? Could I go to the 2.3L motor for some more performance, or even the 2.5L for performance and reliability?