here is the LINK to the neco howto do precats...
i can't believed you removed the rear one... it is a b*itch. we just gut in on the car.
we've found recently that even removing the y-pipe completely is uneeded. just unbolt is from the manifolds, maybe take down an exhaust hangar or two and push it out of the way.
a couple of weeks ago we did three sets in one day
here are the pics ... almost nearing 100% gutted in
MC-NECO