Nope, not any different grades for the suspension bushings
I have the full Hardrace bushing kit in my car with yellow Koni's and Eibach Pro springs and i love the way my car feels. It's stiff, but the car responds so well!
have you driven a type r before? My EP3 is completely standard and many people I take out in it complain about the ride quality as they are used to normal cars
This is probably the answer. Would put the bushes under extra tension before even seeing a bump. This makes it a lot more bouncy than they should be. Just give this ago before buying anything or selling the car.