To start,I was not overly happy with the sound system in this vehicle (16 is350F) so i have been lurnking and reading up on upgrading. I am no car audio expert-- these are just my experiences.
So far, i have only done the front window/dash speakers
I pulled the stock ones out-- wow they were light and cheap feeling.
I was hoping to increase mids and get better highs--so i got 4" coaxial Infinity reference speakers.
It DID take some modification to get these to fit-- some plastic needs to be trimmed in the speaker hole and i needed to spread out the mounting tabs on the speaker as the bolts used to hole in the speaker were bigger than the mounting tab gap.
The right side there is a vent tube in the way--so that one i had to tilt the speaker a bit to get it to fit.--not ideal, but managed to get one bolt to hold it.
I also had to modify the speaker grill to allow for the bigger speaker (trim some thin plastic on the inside of the grille)
I attempt to put a speaker backing/foam behind them-- just couldn't finagle it enough to fit in there correctly--so junked that idea.

the METRA speaker wire adapters (8104) are NOT correct for this location (dash) i did find some that fit perfect on amazon:

the bad:
After all this, the highs ARE a bit better, but I get ZERO mids--so i am guessing these fronts are choked off to limit only the higher end (basically tweeter only.) ---lesson learned If i was doing it again-- i would just find a good tweeter for this location

I will probably look at the front doors next to see if that will help. Just planning on putting better speakers in, and dynamat the doors while in there--might be a summer job

I did dynamat the trunk lid-- MUCH more solid (sounding) now.

 

update-- i just ordered some 3.5" cone tweeters (auto) to try instead-- will let you know how those work over the 4"
i think the dedicated cone, 3.5" will sound and fit better up front.

worth a shot anyway...

 

I installed Focal ICU 100 4" speakers in the front dash, they sound fantastic to me, but I do have them hooked up to an Alpine PDX-V9 Amp and LC7i Audio Control Unit so I was able to dial in the crossover to the the frequencies I wanted.

I had planned on doing the front door speakers, but after doing those Focals in the front and some infinity kappa's in the rear, I'm not even gonna bother with the front doors as it sound great right now.

I have my amp powering my Focal dash speakers, the OEM front door 7" speakers, and my sub in the trunk. Then my stock headunit powering my rear speakers.

 

what rear ones did you do? the rear doors? apparently my 16 only has one speaker in the back deck (sub)

i thinkt the 4" ones i put in would be great, up therre--if the werent dialed in to only the highs from the factory.
I dont plan on a amp at this time. I not quite ready to go that far ....yet

 

I edited my post above to include a little bit more info, but I put the infinity Kappa 6.5's in the rear doors.