I need some help. I will be installing an amp and subs into my 09 honda civic coupe and I dont have a aftermarket headunit. I just have a the regular stock one. How do I go about doing this?

 

You are going to have to splice into the rear speakers and install a hi-lo converter. Basically it has a pair of right and left wire inputs and a pair of RCA outputs, then you have to use your amps built in x-over to cut out any highs going to the subs. I would say set your low pass around 80hz.

Hope this helps.

Note: a new HU makes EVERYTHING sound better.

 

Also to add to the above comment, if you have the factory sub and sub controls at the radio, you can splice into those wires instead of the rear speakers. this way you will keep the sub adjustment at the radio. If you have the factory sub, it would be mounted on the rear deck in between the two rear speakers.