I just bought an Ibanez RG2550Z brand new off ebay and it came with DiMarzio Evos, in all 3 positions. I don't like the way the evos sound in the guitar and I already had a plan of getting the 2550Z and putting a Steve's Special and Air Norton in it. So my question is, what is a great single coil pickup (preferably from DiMarzio) that is a good companion to the Steve's Special (or D-Sonic) and Air Norton. I will be playing mostly shred stuff on this guitar and Dream Theater covers. The mainly it will be a DT/ Prog Metal/ High Gain shred guitar.

I am also planning on trying and maybe buying an RG1550M and a RG1570 as well. I would like some single coil suggestions for those two guitars as well. For the 1550M I am going to be putting in a Super Distortion and a PAF DP103 in it. And I will use it for Iron Maiden, Judas Priest songs and covers/original stuff in a NWOBHM, older Heavy Metal and Classic rock style on this baby. So I'd like a single coil that can match those two pups and do like David Gilmour and Stevie Ray Vaughan/Jimi Hendrix bluesy style exceptionally.

For the RG1570 I will be putting in a Tone Zone and a Humbucker from Hell to get an older Paul Gilbert an DT sound (I&W) as well as some 80s shred/hard rock and some lower gain noodling stuff compaired to say the RG2550Z I currently have.

I have picked out a few single coils already for each but don't really know how they will sound in the middle position flying solo or running with the other humbuckers.

Those pups are:

RG2550Z: DiMarzio YJM(HS-4)

RG1570: DiMarzio HS-2, HS-3

RG1550M: DiMarzio Area '61, '67

Thanks for any input or suggestions.
I know this isn't much help, but it appears you're not getting any... Overall, you can't really go too wrong. I would go with the YJM if I had to pick from the list, as it should be a good pickup for shred. Personally, I'd get the hum-canceling kind, but that's just me.