audio question

So I bought all new speakers plus a deck today and I ran into some problems. The deck and rear speakers mounted fine. But I have infinity for the front and they have a built in tweeter. Therefore the cone is off centre and it won’t fit in because of the amplifier behind it. So my question is do I need that amplifier or can I get rid of it

there is an amplifier mounted in behind the front speaker? if there is and it is causing the new coaxial speaker to not fit, remove it. the new speaker can be powered either by the head unit or by an aftermarket 2/4 channel amplifier.

what size if the oem front speaker?

Yeah you have the new deck so you can rid your self of that amp. I believe the new decks produce the same wattage out put as the amped s13’s did. If you were running the stock s13 deck then that’s different.
My car had the amp before someone removed it… Just check the plug going into the amp (if you are going to use the stock wires) I believe the amped s13’s came with a plug with 4 wires 2 wires are for your sound the other two i think are for power to the amp.