On a G car yes. It took about 24 hours off and on and lots of four letter words. Are you doing a Stevens body??? If not I will walk you through the bleeding and what it took. If you are doing a complete exhaust system with a catalyst there is an whole other issue if using Alunox supplied 3 inch exhaust. Vivian had his daughter weld in a custom made exhaust system. The lower tub on North American cars is different then the ROW cars without catalyst. One thing to keep in mind is the oem header is notched out and some of the nuts are hidden. 1/8 and 1/4 turn backing off with custom "adjusted" wrenches to fit in. Also lots of heat three times with a banging device and penetration oil. Some nuts will not come off until the manifold is moved away from the head. New nuts will have a 12mm size and easier to work with on the reinstall instead of the 13mm. RDENT and JAE both have them in stock. We also used them on my sons Jensen Healey, although they had a factory header and easier to work with. Wrapping the exhaust is no small pleasure either and extra set of small hands come in helpful. Lifting the engine on one side doesn't help either. The blow off valve is a bit of a hassle on the G car , again its space and the caution needed to not damage the turbo oil return to the sump. Small hands are certainly an advantage and a ample supply of bandaides. Penelope and I are blood sisters at this point. Pulling the lump is probably faster, easier and you can toss a new belt on at that time :grin2:
OMT,, have ample supplies of the alcohol of your choice nearby.
I just did this on the '95 s4 with engine in place.
After lots of expletives I tried another idea: here was the trick: undo the engine mount on the same side as headers, lift the engine slightly. Also pre-bolt the old manifold to the allunox to align them first, and then carefully move to the engine. It went on really easy after those two steps...