TTI instalation question

I have had a set of TTI's for over a year and I am finaly going to install them(moved last year you know what that is like) I have not read the instructions through but have followed several threads on instalation.I read that the front end must be jacked very high. This seems like a dumb question as I write but here goes, I have a 4 post hoist in my shop, will it still be necessary to get the car angled up in the front or will I be good to go if I have it up in the air? I seem to remember something about suspension parts being in the way, therefore the front end needs to be up high??
Thanks