I have a '95 A6 FWD. I am reinstalling my catalytic converters after an engine gasket overhaul. I separated the left and right cats when I replaced the bolts at the rear flange and front bracket. During my first attempt an reinstallation, I discovered that the top flange bolt was rather difficult to get to since I didn't have an obstruction wrench. So, I decided to assemble the two cats before reinstallation. I held the bottom of the left and right cat to a flat surface, tightened up the flange bolts, then tightened the bolt at the bracket. I then hoisted the assembly into place, placed a bolt in the hanger and through the cat's bracket, then pushed the cat's front pipe flanges onto the exhaust manifold studs. I had to spread the cat's front pipes slightly to get them to go on the exhaust manifold studs, I then tightened the exhaust manifold nuts per the sequence in the Bentley manual, then tightened the bolt at the hanger. The Bentley manual states that the distance between a line drawn between the bottom of the cat protectors (those upside-down U-shaped things) and the bottom of the cats has a max value of 0.47 inch, but the distance I measure is over 0.5 inch, so my cats are sitting higher than specified. My question is this: is it permissible to install the cats as one assembly, or should I install each cat, tighten the exhaust manifold stud nuts, tighten the cats flange seal and bracket bolt, then attach the hanger bolt? How critical is this distance, and if I assembled the cats one-by-one, would it make a difference? I also noticed that the flanges at the exhaust manifold are not separated by an equal distance. Both left and right flanges have a greater distance on the engine-side,so I am concerned that the flanges are not mated properly. Any thoughts or suggestions would be greatly appreciated. Thanks!