i was thinking about customising my bass which is p j set up in fact its a squire but i wanted to put in some pickups that have a metal sound of heavy im not sure how to put it any ideas.
There isn't really any such thing as a metal sounding bass pickup - there are plenty of examples of bassists in metal bands using P, J or humbucking pickups. What kind of sound are you after?
well a metallica, soil and a bit of rage i dont really know much about pickups im fine with electronics and pots and blah but pickups i have know idea.
I know quite a lot of local metal players who changed the pickups in their fender basses to EMGs, and the result works really well!
Ibanez SR505
Ashdown ABM 300 EVO II
Epifani UL410
Cliff and Jason both had different basses Alembic, Spector, Rickenbacker, some basses had single coils, others Humbbuckers. As others said its all about your EQ.
i have ibanez gsr-205 and i am planning to upgrade it with new pick-ups i guess humbucking pick-ups...will it be fine or else i need something else to deal with it?? i mostly play death metal
I guess there isn't really a hell of a lot of people that have extensively tried different Pick-Ups and done side-by-side comparisons etc

**Woah, you should see/hear this interview with Jon Schaffer of Iced Earth - The Rhythm Guitarist (influenced by Steve Harris no less - odd, I know) He actually, now having money, tried out like every known Pick-Up he could get in his main recording Guitar, till he found a couple he loved for specific sounds etc. -----Point of that is------- I wonder if anyone has done something similar with Bass PU's .......? Hmmm

Anyway, I'll do the mandatory answer until someone can answer that^.
fatgoogle, I'm gonna say that any High-End Pick Up set would help heaps over your stock PU's. As well as mucking around with your EQ (as Charlatan_001 mentioned), having Low Mids can help but can also increase Muddy-ness - depending on your EQ range etc

The increase in 'Pick Up Ability', for lack of a better word , will help bring out that Aggressive Metal picking/plucking technique you've hopefully been working on .

And on the topic of Technique, having good control over whatever Bass style you use (Fingers/Pick) and then applying that technique to the Neck area of your Bass to produce a almost percussive sound (kind of like Slap) helps with getting "That tone" you are seeking.
|Sorry for the massive post|
its ok i sort of get it so my eq fairly good but about emgs are those the ones that need a battery and a preamp and if yes are they difficult to install. If i choose some fender pickups or something i can still get a metal sound with the eq
What amp do you have? Chances are it'll make a hell of a lot more difference to put the money towards an amp rather than modding a Squier.
well i have a fender rumble 100 watt combo but at the moment i dont have eonough money to get a new one (that would be nice to). and i dont need a new one badly as in when i gig they have all the amps there