I have a 2006 Honda Civic EX 4dr. The stock head unit is, 140-160 watts (dont remember. The coups version has 350w. Is there a way to keep my stock head unit and be able to increase the wattage by replacing the amp in the unit or swapping out coupe head unit for my own?

I am not in forever of installing a new deck.

 

Don't waste your time replacing the internal amp, just buy a new radio or go with an external amp if you want more power.

 

I have an external amp... it is a single channel though. Would that work?

 

For a subwoofer yes, to power your interior speakers.....no

 

So without changing the head unit. What would you recommend to do to get more sound on the internal speakers as well?

 

If you still have stock speakers, I wouldn't recommend anything more than a "mini" amp that you install behind the radio. Something like the Alpine KTP-455U. Anything more and you run the risk of overpowering your speakers.

 

I will be upgrading my internal speakers to something to handle more wattage