Does anyone know what the available options are to stiffen up the suspension on a 2018 IS 350 F Sport AWD without lowering it?

 

Stiffer shocks, but it's probably a waist of money without springs. You can look into the OE Aftermarket F-Sport springs for a mild 1" drop. You can also go full coil-over and set the ride height to stock spec.

 

The answer would be a coilover kit. RSR Sport-I coils are top notch I've been riding them for 20k miles already. You can have them adjusted stiffer and leveled to stock height, or higher, or lower. It really gives you so many options.

For the winter I put the car to stock height, maybe half an inch higher, installed snow tires and drove the car back and fourth to PA, NY, and Vermont all winter from NJ for snowboarding.

Now I have the car lowered with new wheels with 0 wheel gap for the summer. I think RSR even makes a kit that's compatible with AVS these days.

http://www.rs-r.com/product/lexus-is...oilovers-2014/