Efficient Speakers

[Count]

I'm new to car audio upgrades,etc.

Was in a car audio shop recently and the lady recommends a set of Pioneer 6x9 speakers to replace the factory door speakers in my 2006 Tacoma DC. She tells me that I can run them off my factory head unit, because they're "efficient."

Don't know what this is all about, but can anyone recommend a good type of "efficient" door speakers? I want to replace my factory door speaker in my truck. No particular budget.

I just want the music to sound better, clearer. Would I need to replace the tweeters, as well?

Thanks,

Count

[LiquidClen]

Keeping Stock radio? Amplified or unAmplified? PS round speakers (such as 6.5") sound better than elliptical speakers (such as 6x9)