Each fan comes with 3 sets of screws:
4x self tapping screws for mounting to case panels
4x 36mm screws for mounting on radiators
4x 39mm screws for mounting with Halos on radiators
I've been playing with 3x T30s in my Evolv mATX build in daily use conditions. Not much but lower cooler intake air temp. Not a big difference in this application, but on a radiator I suspect difference to be more evident. 3x T30 definitely move more air than stock MP impeller case fans at same noise levels to my ears. My meter died, but from previous experience my ears notice a 3dB change in volume, but not 2dB. I'll have a new meter soon and add dB data.
As soon as new meter arrives I will do some heavy (extreme) load stress test runs and post results