Door speakers:

JBL CLUB6520 6.5" 300W Club... https://www.amazon.com/dp/B01KW1F6ZA?ref=ppx_pop_mob_ap_share

Seat speakers (somewhat underwhelming no matter what speaker you put there)

JBL GX302 3-1/2" 75W 2-Way GX... https://www.amazon.com/dp/B00O8MNNT6?ref=ppx_pop_mob_ap_share

And stereo (love every bit of it):

JVC KD-R690S CD Receiver... https://www.amazon.com/dp/B0771BDVDB?ref=ppx_pop_mob_ap_share

Thats all that i have installed in my NA, and im a music producer, it sounds really good, but to be honest at high speeds (in my country you can go cruising at 100mph) the wind and engine sound will get in the way, even with a hard top.

But to be honest the one i had in the US was inferior to these ones and sounded good too, so if you are in the US with speed limits and stuff, this will be enough and easy to install.

was curious how you guys managed to upgrade your old speakers, I realized you have to take the door panel off (right?)

And wondered what type of aftermarket speakers would fit, or what type of modifications would need to be done

Option 1? 4 x Pioneer TS-G1620F 6.5-inch 2-Way Car Audio coaxial Speakers 6-1/2" with DiscountCentralOnline 25ft Speakers Wire https://www.amazon.com/dp/B077NWCPML/ref=cm_sw_r_awdo_navT_g_A6XD3DN0G3X6FQ89BWN4

Option 2? JBL GTO629 Premium 6.5-Inch Co-Axial Speaker - Set of 2 (Renewed) https://www.amazon.com/dp/B07S9L5S55/ref=cm_sw_r_awdo_navT_g_4AZVHCGKDGRPER82VB6A

Option 3? 4 New Rockford Fosgate R165X3 6.5" 180W 3 Way Car Audio Coaxial Speakers Stereo https://www.amazon.com/dp/B00E81RAU0/ref=cm_sw_r_awdo_navT_g_Q67WM7HG8BA999QZXH5W

Option 4? Kicker DSC650 DS Series 6.5" 4-Ohm Coaxial Speakers - Pair https://www.amazon.com/dp/B01BLVEVNS/ref=cm_sw_r_awdo_navT_g_36HH2HXRMMD32Z0ZC2V3

Option 5? JBL CLUB6520 6.5" 300W Club Series 2-Way Coaxial Car Speaker (1 Pair) https://www.amazon.com/dp/B01KW1F6ZA/ref=cm_sw_r_awdo_navT_g_4G7XX8KAMBA12BH2XPKD