I almost installed Wheelers superbumps on my 99 4runner, but instead went with Durobumps and am so glad I did. I think the Durobumps are higher quality, better rubber, better engineered and most importantly (imo), the fronts are made with an angled bottom. That when compressed, makes full contact with frame member. In my research, there were quite a few complaints that the Wheelers Superbumps contact the frame at an angle, so only a small portion of the bump stops is taking the force of impact. And some guys noted premature failure due to this. I hope that makes sense.
I installed both front and rear, and have had them on for about 5k hard offroad miles and I am very happy with them. They far out perform the stock bump stops. Washboard roads are now tolerable...
Good luck with decision.
Durwin