I was thing of replacing my " stock exhaust manifolds/headers" on my stock 89 GT. first I was looking into the what seemed to be the easy shorty upgrade , but wonder about the possibility of putting LT's on instead. First I will have them installed so I would not be dealing with the garage install. I stick with what I know and what I my limits are, exhaust work isn't my area of expertise. I will have to get the matching X Or H installed at the same time so I will give someone the opportunity. So that being said, I have read about some interference the LT headers may cause. Have also seen different brands that claim to not interfere. Just figure my stock 5.0 has 54K right now so I could potentially bolt on some HP down the road, so why skimp now and if I later decide to drop something else in I could use the LT's and remaining exhaust. I read that the LT's have to be removed to change the clutch, and I'm sure that will be on my list of real soon replacements. I would rather bolt on the max HP I can just don't know if the LT's will hinder me until I get some more HP.