i'm getting my sub in my car pretty soon i was wondering if i'm suppose to cap of my speakers so that no more bass comes from them. my head unit and speakers are stock, and the sub that i'm installing is a rockford fosgate he2 (400/800 rms/max).

 

What you should do if you can is run a high-pass crossover. This cuts the bass out of the signal going to your speakers. This way, you leave the bass to the subs and the rest to the speakers. Then you'll be able to get more volume from the stock speakers, since they aren't being troubled by the bass.

 

At least add a set of bass blocks( capacitors ) to the main speakers. An 80-100 hz cutoff frequency would probably be a safe setting to go with.