it isnt that hard for someone who knows what they are doing. midpipe will have to be adjusted, but shop will know how.Honestly, I have no idea about emissions. We don't have that here in Iowa. I think long tube headers will require some slight modification to your midpipes and your oxygen sensors will needs extenders.
My friends 98z was.... like 2' off the ground and his headers (SLP long tubes) were about 1.2' off the ground... he Daily drove that car fine.well i just did not know. because i know some of my friends have lts on there cars and they are not mustangs and when you look under the car which is not lowered the headers hang way down.