Last year (or I guess it would be two years ago now that it's 09), Peterson's had a Jeep JK suspension shootout between 9 or 10 different companies. Basically, they sent an invitation out to all the major companies and those who wanted to enter were furnished Jeeps to equip with their setups, and a day was set for everyone to meet in the desert for the "test". Needless to say, The Black Diamond (same as Superlift) Jeep scored higher than all but one other company, but was only surpassed by a marginal degree. Plus, the winner's setup cost more than three times as much as the Superlift and actually had a few broken parts before all was said and done, unlike Superlift's jeep. Trailmaster finished dead last.
For the price, you'd be hard pressed to find a better performing setup than the Superlift kit. They are ruggedly built and take many more things into consideration with their designs than many other companies, often at a comparable (or cheaper) price. Their superrunner steering system is just plain awesome, in my opinion. Skyjacker also makes excellent stuff as well. Just my opinion, anyhow