I too have a SA 1911 9mm. Anyway, mine came with a 9lb recoil spring (per Springfield), and I replaced the ILS with an Ed Brown "wedge" mainspring/mag well
I install a 23# MS, and everything feels, and runs like factory new. trigger pull is about 4.5#'s.
I also picked up a 19# (reduced power) mainspring, and with that the trigger pull is about 3.5#'s., but I have not tried it yet (at the range). I kept the 23pounder in there for the match I was getting ready to shoot
Will keep you posted...........
Hope this helps