any bro have install those spring stiffener that claim to pro-long the life span of original spring and at same time offer stiffer ride.
years ago, one mechanic ever advised me not to add on anything to the original spring as it will affect the braking reaction the car and at same time the safety handling.
have called to enquire - for suv - it is not cheap - will probably cost 240 dollars for 4 pieces of rubber...