Here is a collection of S1 engine bay photographs.  These pictures are of the S1 engine with the Lehmann tubular exhaust manifold shown below.  SOme of the pictures have the dual wastegate shown in the 1st picture below.  This was Audi's anti-lag system.  The 2nd picture is the same exhaust manifold with the anti-lag system removed.  The holes in the flange have been plugged.   In the series of pictures that follow, S1 engine bays can be seen with both setups. Some have dual wastegates, other do not.  But all pictures have the Front facing air intake as opposed to the Air intake by the firewall which seems to be the system used when the Sport Quattro Exhaust manifold was used.    This exhaust manifold used a Wastegate and K27 turbo from a Porsche 930.  The 2nd wastegate is from a Porsche 944.

Single Wastegate.  The Constant Air manifold is still piggybacked on the Exhaust manifold, but the point for the 944 wastegate is sealed with a plate.

This car is in Vegas and is for sale. I believe it has the same setup as above with the piggyback manifold present, but sealed off.

here is a mechanic working on an S1 rally car (not hillclimb).  The Anti-lag system was tried on late 1986 cars in an effort to be competitive.  They were obviously one of the reasons the Group B cars were so dangerously fast.  This picture is fascinating because it shows some of the intricate vacuum lines which were used to control the wastegates.

Top down view of what I believe is the 1987 Pikes Peak Hillclimb Car.