when i play i RnB song my subs sound really good and they pump mad, but when i play dance song where the beat is fast the subs seem to lag, like they cant keep up with the song ur some thing. Can some one pleas help???

I MAY have an answer for you.
What size are your subs, anyway?
In my experience, the louder the beat = the further the speaker moves. If you are listening to a song which has a fair bit of bass, but is fairly laid back in tempo, the subwoofer has more time to beat, then return to its normal spot quicker, but if you are listening to a song with a quick bass beat, the subwoofer can't return to its normal position in time before the next beat in the song, which makes it sound flat, or gives you sound pressure on the 'up stroke' if that makes any sense, sort of giving you that 'doo-WHUMP' sound. You'd probably notice that this only happens when the music is loud too. My advice:
1. Turn the bass down a smidge. let your midrange speakers work for you.
2. Look at how your subs are wired up. Try and isolate the power to each so one is at full power, the other at half. this will give you a more 'real-time' response at loud volumes.
3. Reverse mount one of your subs. Noise from the front of one speaker into the box will give you quicker response.
4. More powerful amp. Even think about one of those huge 1 farad capacitor things which keep the power up to the amp at a constant 12v even with heavy bass.
5. Get bigger subs. Depending on what music you like, Configure your subs to suit e.g. general radio stuff usually gets by on 10"s. Metal & Ambient stuff is great with 10" & 12" subs for the 'punchy' factor, or one of each. Techno/RnB stuff i'd imagine would be great with 12" - 15" speakers for the electronic bass pulses.
Now i'm just rambling.
Hope that helped.

please tell me what subs you have so i dont get them!

hehe

i sorta know wat your talkin bout and i think leigon pretty much said it all... i dont have any probs anymore.. 2x 12" 350wrms d.v.c pumpin hard on a 400wrms amp..so heavyily underpowered..but one you go dual voice coil you'll never go back well i know i wont. the defintion and depth you get with d.v.c compared to singles(that ive heard) is just outstanding,

Well according to physicists the louder any type of bass the laggy it basically gets due to the cone having to travel further then when quiter bass. Usually the larger the subs the lower the bass, but due to lower bass the cone travels further in the linear taking time for it to come back to produce the next wave and if you play dance/trance (doof doof) with a fast bass beat the cone may be too slow to keep up with the beat. The free-air resonance decreases as you go up in size, so if you want good bass for doof doof you should go for small sized subs that have a high resonance. Or something along those lines.

I may be wrong or used to wrong terms...

phong =P~

Dual voice coils sound exactly the same as single voice coils, the only difference is wiring options. The reason you think your DVC sound better is because you probably changed the TYPE of sub you were using.

Yep simply flexibility with wiring and installation...and can effect your options when buying an amplifier....however having SVC,DVC or even QVC (Quad voice coils) the difference between, in output both power and sound, clarity etc is bogus there is no difference at all no matter the number of coils...Having woofer lag too can also be to do will the enclosure setup ypu have .... maybe being too large or small...like the effect you notice when cranking woofers with the boot closed and then the difference in the audible sound when the boot is then opened.