For your .45, I recommend a 16 lb Wolff Spring, as that is what I run in my older Standard .45 Witness.
Stock No. 49816.....EAA Longslide pistols only....
Stock Spring weight will be about 14 to 15 lb's. Tanfoglio Recoil Springs, while rated at 14 lb's, really tend to be more like 15 lb's.
For my newer Wonder Finished .45 Witness, I've seen fit not to change anything as yet. When it is a little more worn, say 10,000 rounds down the road, then maybe an upgrade to a 16 lb spring will be called for, as the hammer spring and recoil spring will have some wear on them!