Pickups

Hi to all!
I have an Ibanez RG550 with v8,v7,s1 pickups.
I like heavy metal a lot so I want to change them with some DiMarzio's,but i have some doubts:
in the bridge is better a Super Distorsion or a Super 3?
in the neck is better a Super 2 or a Humbucker from Hell or an Air Norton?
What do i have to put in the middle?
What about a Dual Sound?What are the differences from Super Distorsion?
I hope someone can help me!
Have a good playing!

I personally perfer Duncans. I think (not 100% sure here) Alex Skolink (might be Eric Peterson)uses a Duncan Full Shred in the bridge now.
DiMarzio wise, I've heard some good things about he X2N and the Tone Zone. I wouldn't worry too much about the neck and mddle pickups right away, since metal uses the bridge humbucker almost exclusively (but of you do plan on using that neck pickup, be sure to replace that crappy stock Ibanez one).

Thanks a lot for your advice!
I think that with a full shred i will have too much highs!
I prefer a fatter sound in the bridge like Paul Gilbert's last album with Racer x,and i like Megadeth "Rust in Peace" sound for solos or Timo Tolkki's sound in album Destiny.If you can give me any other help,i'll be grateful.
Good Shredding!

Just go to http://www.Dimarzio.com to find out which pickup best suits you. And make sure you place the humbucker with the most output in the bridge position otherwise it'll sound unbalanced. The X2Ns' have 520 millivolts of output making them Dimarzio's loudest. As far as tone goes you'd really have to check out the site and decide for yourself. Good luck.