HELP - rear coil spring codes and spring rates

[Carbon23]

'21 Limited - Now that I have the Traxda 1.5" spacer lift installed, I'm getting WAY too much rear end squat on hard acceleration (any drive mode), which lifts the front end up too high causing steering issues. Feels like torque steer because the front is at or near the top of it's travel. Light acceleration there is no problem, steering is normal and handling is what's expected from a spacer lift. Tires are 32" Falken AT3 at 33 psi (tried various pressures but no difference). So I'm looking for ways to stiffen the rear.

My first thought is to try air bags at various pressures as a test. They are cheap and easy to install.

Second thought is to use stiffer rear coil springs but I'm having difficulty finding any specs on what the spring rates are. I would venture to say the PIU spring rates would be a little stiffer but the length might be shorter. Anyone have a source that lists the coil spring lengths and codes and their respective spring rates for all flavors of the gen6? I could only find the various part numbers but no specs.

Third thought is to replace rear shocks with Bilstein 5100's which might help with initial damping at the top of the shock travel right before squat starts.

I'm out of thoughts now. What are yours?

 

[slow3v]

I'd replace dampers first, they will make a measurable difference in nosedive/squat in my experience. How is the rear lift achieved if the OEM springs are used?

 

[Carbon23]

I'd replace dampers first, they will make a measurable difference in nosedive/squat in my experience. How is the rear lift achieved if the OEM springs are used?

Yeah that's my thought as well. Trying the rears first. Going with Steeda Pro Action. Rear lift is achieved with a spacer above the coil spring. I also installed Air Lift coil spring air bags with 10 psi to start and that helped some but did not eliminate the issue. Don't want to go much higher pressure when empty because the ride will be too stiff. Maybe in combination with the shocks, I'll have more controlled weight transfer.