Location isn't the issue. It's speaker design. I use a subwoofer in my trunk and everybody looks around trying to find it up front. They seem to think I've hidden it

The other issue behind localization is vibrations. Some people go as far as placing sound deadener on the underside of floor mats to prevent localization through vibration. I believe a 20hz wave is 54 feet long or something rather. Everything it hits on the way out tells us where its at. Dampen that out!
Installation is key to success. Good audio isn't the product of spending money, just making good choices based on goals. Purchase speakers based on needs, not reputations or bragging rights. Every speaker is different.
EDIT: I only use 300watts. Theory states that 600watts = 3db gain. Research shows that 3db is noticeable to our ears but isn't perceived as much louder; 10db gain is perceived as twice the volume. 1watt sensitivity is what you want to look for when trying to get LOUD. You don't necessarily need 1.2 jigawatts :>