QuestionI've got a 2005 Kia Spectra, and I love the car enough to have upgraded it already in a few ways. I'm looking to replace the factory with some aftermarket ones. I'm not sure if I need component or not, either way I need something that has a high wattage rating as well as a great sound when I plug it in.
AnswerUnless you replace the stereo, high wattage speakers won't be any louder than what you have. Even then, the most an aftermarket stereo puts out is roughly 18 watts RMS per channel. If you want more than this, an amp is in order.
I prefer components simply because I can design my system to how I want (I'm an SQ guy [Sound Quality]). However, a component system can be difficult to design and implement, that pesky molding always gets in the way. Coaxials are less of a task but I feel they lack the control.
Look for CEA-2006 compliant head units.
Go here http://www.metraonline.com for any install accessories you may need (factory wire adapter harness, install kit, etc.).
Good luck.
