Simo,
Im running 2 x 10 inch Calibre Thermofans that i found at Super cheap. Not sure if they were less than 5.5. I used 2 so i didn't contact the water pulley and harmonic balancer etc in the middle of the radiator as you would by using a single fan. I can check later tonight. See attached photo for what i did.
I know its not as efficient as using a single fan, so i placed one fan close to the entry side of the radiator and one close to the exit to give it just that little bit more of a chance to cool the coolant down.
I also used the pull through fan setup to allow the front of the radiator to get a full surface area for cooling rather than blocking it with the fans. Its going to have enough trouble with the intercooler pre heating the air. I may eventually put a few airflow diverters in to compensate.
Im hoping the larger alloy radiator will be my saving grace
