Ground Control coilover sleeves are indeed very nice.

They also have pretty stiff spring rates which means you should upgrade your shocks to go with them. The G2 ('90-'93) Integra doesn't have a lot of suspension travel so lowering the car and using a stiff spring puts a lot of strain on the shocks.

Another option to look at is the Tein Super Street full coilover setup. For other cars I'm not so much a fan of Tein given their price and other available options, but for the G2 they actually have a really nice setup that has shortened shocks which help to deal with the really small amount of suspension travel. For a G2 teg it's a lot more important than other cars to have shortened shocks. They're not super cheap though, about $950 for the set. Tein also makes a coilover kit called Basic which is about $715 and has shortened shocks but they have fixed damping as opposed to adjustable damping of the Super Street kit.