Where did you find a cold air intake for an 89 GT???? I know exactly what hoses you are talking about too. If you read my post about the Home made cold air intake I mentioned putting baby K&N´s on them. The hose to the engine is basicly the breater part of the PCV system. Putting a filter there is a really good idea. wouldn´t want to be sucking dirt into your engine. The other two I believe have something to do with the catalitic converter. I xant go look at mine right now because it´s pretty dark, but I know at least one of them goes to a long metal tube that if I remember correctly goes to the side of the cat. And I think the other hose goes to another part of the smog system. If you are in a place that does smog check I would recomend keeping your old airbox as much intakt as possable so you can hook them back up when you go to get it checked. If you don´t have to do smog checks, then you shouldn´t have to worry about it too much.