Does the multiplier for wielding a weapon two-handed apply to my Dex mod if I have the Weapon Finesse feat?

I have a rogue with the Weapon Finesse feat:

When making a melee attack with a light weapon or rapier, you may use your DEX Mod instead of your strength Mod on the attack roll.

Since a rapier’s hands datum is 1, I can wield it two-handed:

If you wield it two-handed, add 1-1/2 times your STR Mod to melee damage instead.

If the character’s Str mod is +1 and Dex mod is +3, and they have the Weapon Finesse feat, is a two-handed attack always +1.5, or can it be +4.5?