Honestly I haven't seen much that proves aftermarket cams helps a ton on the X's. Maybe on pump gas, but on e85 it seems that you can already max the setup out. So if you plan to stick with pump, then i would think the cosworths would help for sure. On Buschurs dom2 setup on pump they picked up 40whp/40wtq on their dyno, which is what convinced me to buy them.
I will let you know if i sell them
Edit: honestly, i thought my setup was pretty damn simple...especially my stock turbo setup, i only upgraded what was needed, aside from cams which i was a test bunny for everyone to see if it helped the stock turbo at all, which it didn't.