Will an SiR radio install into my 5th gen without modification?

 

it will "fit" but you will need to make sure its secured in there good, all you should need a is a backstrap.. also to make it "work" you will need a new wiring harness adaptor from a 99+ civic.. you can get a metra met 1721t (think thats the model) basically get honda reverse harness and wire it to the harness thats already in there or get a metra 1720 harness and wire it together like a normal radio harness and your good to go..