Upgrade factory speakers to 6x9 3-way?

First, is there a spec list of what the factory audio system contains? I took a look at the 2nd Gen Audio FAQ but I didn't seen any mention of speaker sizes. Long story short, I've had some Sony Xplode 3-way 6x9 speakers in a closet for the past 10 years. I purchased them for a previous car but never used them. Would 6x9 3-way speakers be a good replacement for my factory speakers? Is it simply a remove the old and replace with new or does it require a special harness and/or speaker mount?

Sony speakers
http://www.cnet.com/products/sony-xs-v6920-speaker-for-car/specs/

 

You will need a set of adapters to fit the speakers in the door... something like this

$19 Metra 82-8146 6" x 9" Front Speaker Adapter for Select Lexus and Toyota Vehicles, Black, Apple

http://www.amazon.com/gp/product/B00IIC6CPE/ref=od_aui_detailpages00?ie=UTF8&psc=1 will work.

You can either clip the stock speaker wires and solder them to the new speaker, or crimp on some female quick disconnects, or get a set of these adapters

$10 Metra 72-8104 Speaker Connector for Select Toyota Vehicles, MULTI COLOR

http://www.amazon.com/Metra-72-8104-Speaker-Connector-Vehicles/dp/B0002BBP7Y/ref=pd_bxgy_e_img_y that plug right into the stock harness.

Some people leave the stock tweeters wired. Others have reported that if you want to disconnect the stock tweeters, that disconnecting the tweeter harness also disconnectes the 6x9s, so you need to clip the stock tweeters at the speaker terminals. But, I haven't tried that myself.