STU Option

[Visceral]

And the 700/1000 springs may just be transferring compliance into the subframe. The Powerflex look like less metal than stock, but I don't know how stiff "80 durometer" is and it its worth the labor of dropping the subframe for. At least I'd feel more comfortable with the likelihood of noise from changing out the diff mount bushings to powerflex as well.

[Visceral]

I should also be clear that I'm a crappy enough driver that no one will ever protest my near-last results in local Pro-Pax competition.

[Richbot]

I don't think the subframe cares what springs are on the car, it moves fore/aft, side-to-side depending on how much load you're putting into the rear suspension through the tires and drivetrain, it won't deflect more unless you're cornering or accelerating or braking harder in other words

[Visceral]

Originally Posted by Richbot

I don't think the subframe cares what springs are on the car, it moves fore/aft, side-to-side depending on how much load you're putting into the rear suspension through the tires and drivetrain, it won't deflect more unless you're cornering or accelerating or braking harder in other words

My thought would be that stiffer springs increases deflection of the subframe bushings under high cornering, accel, or bump loads.