The Envision and XT4 share the same chassis. The reviews always praise the ride of the Envision, and complain about the ride of the XT4. I checked OEM coil spring part numbers online for both cars, and the part numbers are different. I am assuming that the Envision springs have a lower spring rate than the XT4 spring rates. Does anyone know if the Envision coil springs could be installed on the XT4 to improve the ride?