Reddit mentions of Metra 72-8104 Speaker Connector for Select Toyota Vehicles

for the rear I switched it out withthese.
for the front
and
these adapters are great if you don't want to slice the cables.

also. you will need a spacer for the Rockford.

I would recommend the Polk Audio over the Rockford.

Edit: and they work with the stock head unit without an Amp. I am an amateur so I didn't want to replace the stock radio/dash .
and too lazy to add an amp.

Good luck!

Looks like a pretty straight forward swap. https://www.youtube.com/watch?v=kmJwXa9Bkgc

A quick google search and I found the adapters needed to it's plug and play, but do you own verification.
Speaker Mount: https://www.amazon.com/Mosuch-Plastic-Speaker-Adapter-Highlander/dp/B007ZQGZWO
Wire harness: https://www.amazon.com/Metra-72-8104-Speaker-Connector-Vehicles/dp/B0002BBP7Y

As for pro installers. I used to work for CarSpa like 15 years ago in Arlington. They were good back then, not sure about now. They used to do almost all the dealership installs around the area. The boss was a bit of a douche, Yelp agrees apparently.

This is my build which I posted on Facebook a few days ago, before I add subwoofer, so far less than $500, I'm still building it ..

--

Tonight's window-shopping shopping cart for my first audio upgrade from 2016 WRX base OEM audio. Includes amp, speakers, and noise suppression. This seems like a really good starter build for less than $500. Looking for feedback.

DS18 SLC1800.4 DS18 Select SLC-1800.4 1,800 Watts Four (4) Channels Amplifier
http://www.amazon.com/gp/product/B00IDI0D3K/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00IDI0D3K&linkCode=as2&tag=headsense-20&linkId=TLRSTER62FWVZ4YI

• affordable clean wattage
  
• 80 watts per channel matches customer recommendations for the Alpine speakers
  
  Package: Pair Alpine Sps-610c 6.5" 2 Way Pair of Component Car Speakers + Alpine Sps-610 6.5" 2 Way Pair of Coaxial Car Speakers
  http://www.amazon.com/gp/product/B0059AK2T0/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B0059AK2T0&linkCode=as2&tag=headsense-20&linkId=PXNDF7S6RPBZPEKP
  
  Rockford RFK4X 4 AWG Complete Amplifier Install Kit
  http://www.amazon.com/gp/product/B0012BYOSK/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B0012BYOSK&linkCode=as2&tag=headsense-20&linkId=2GAGDGGKMRWMHURO
  
  Metra 72-8104 Speaker Connector for Select Toyota Vehicles
  http://www.amazon.com/gp/product/B0002BBP7Y/ref=as_li_tl…
  
  50 Sq Ft Noico Self-adhesive Foil & Butyl Mat 50 Mil Automotive Sound Deadening Insulation for Cars & Truck (Audio Dampening & Deadener Installation)
  http://www.amazon.com/gp/product/B00URR4O5I/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00URR4O5I&linkCode=as2&tag=headsense-20&linkId=Q7FJEOPI6QOBHJKL
  
  Noico Metal Barrel Roller Installation Tool
  http://www.amazon.com/gp/product/B015WJH4ZW/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B015WJH4ZW&linkCode=as2&tag=headsense-20&linkId=WNEQ67NXUPTXMY4T
  
  BAFX Products® - Decibel Meter / Sound Level Reader - W/ Battery
  http://www.amazon.com/gp/product/B00ECCZWWI/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00ECCZWWI&linkCode=as2&tag=headsense-20&linkId=UV3UKNSI24GV7E3Q
  
  
• to measure the noise levels before and after installing the Noico mat
  
  Dayton Audio iMM-6 Calibrated Measurement Microphone for iPhone, iPad Tablet and Android
  http://www.amazon.com/gp/product/B00ADR2B84/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00ADR2B84&linkCode=as2&tag=headsense-20&linkId=XCRDPQNFVK6NFAAN
  
  
• to calibrate the HU EQ after the amp and speakers are installed

Also if you don't want to splice the cable harness, this works as a plug and play harness

/r/CarAV is better suited for audio questions. To answer your question though, no your car requires 6x9 speakers. You'll need a speaker harness and bracket for a plug and play solution.