I think this topic may have been covered in an old thread, but the archives are not accessible.
For those of you with an older Psychlo-X (pre-'09 or whenever the chainstay was modified for more clearance), what cranksets are you using? Can you get enough clearance to run a 39t chainring with a Shimano/SRAM crank? If not, what's the max chainring size that you are able to run? For Campy, there isn't enough clearance for a 39t chainring, at least not with UT.