I've seen many people upgrade to components or 2-ways. A popular model is the Infinity Kappas. I've been looking at specs for different speakers. The Kappa 62.5i frequency is 45-21k. A comparable Kenwood Excelon KFC-X168 is 25-40k. It looks like the Kappas are more of a mid to high range speaker. The Excelon would probably be not as bright as the kappa but closer to the stock frequency response. Am I making the correct assumption here? The reason why I'm asking is because I want better sound without having to put in a sub.