Francesco,

For SBR of more than 10 I would recommend the 1:1:100 dilution of Pyrocat-HD. Develoment times for high SBR values would be too short in my opinion for the 2:2:100 dilution.

I have test data up to SBR of 13, with DR of 1.6, for Pyrocat 1:1:100 with Ilford FP4+. BTW, amy testing method is based on the standard of gentle agitation in BTZS types tubes. Here is the information.

SBR 13 3:00
SBR 12 4:15
SBR 11 5:30
SBR 10 6:30
SBR 9 8:00
SBR 8 10:00
SBR 7 15:15
SBR 6.5 20:00

For this high a DR (1.6) I don't recommend the use of the 1:1:100 dilution for SBR values of less than 7 (or for any N- development).