That's a good question, I've always wondered about the opposite, I have FE1 and interested in upgrading to FE2 myself.
What part of the US are you in? We might be able to swap springs
Looking into it further, I don't see a different front springs at least for the 2.8L/3.6L CTS the V has different springs front and back but it seems like the front springs on the V6 CTS are the same, the rear ones are different.
Front V6 CTS Spring part# 25739210
Front CTS-V Spring part# 25752925
Rear V6 CTS Spring part numbers:
w/Soft Ride Suspension 25734805
w/o Sport Suspension; Ride & Handling Suspension 25734802
w/Sport Suspension 25734802
w/Performance Suspension 10387989
Rear CTS-V Spring part number;
25752977
What part of the US are you in? We might be able to swap springs
Looking into it further, I don't see a different front springs at least for the 2.8L/3.6L CTS the V has different springs front and back but it seems like the front springs on the V6 CTS are the same, the rear ones are different.
Front V6 CTS Spring part# 25739210
Front CTS-V Spring part# 25752925
Rear V6 CTS Spring part numbers:
w/Soft Ride Suspension 25734805
w/o Sport Suspension; Ride & Handling Suspension 25734802
w/Sport Suspension 25734802
w/Performance Suspension 10387989
Rear CTS-V Spring part number;
25752977