stock S4 manifold better than S5 manifold swap done wrong.

[Whizbang]

That is the conclusion i have come to.

The vert is an 1988 with an original motor. Previous owner had an S5 upper intake manifold installed. Here is something i discovered with this setup.

1. The stub on the Lower Intake Manifold was removed because this does not line up with the S5 Upper Intake Manifold. All other seems to.

2. They had to cut and splice more wire in order for the IAT sensor plug to reach the location on the S5 manifold.

I reverted it back to a stock S4 manifold an here are my findings.

Top end power remained the same BUT you could feel a greater amount of torque much lower in the rpm range. Car seemed to drive and start better with a more consistent ideal. Cold start warm up worked better as well.

Neither had a BAC and all of the emissions systems where removed. So the only change in the idle was from the manifolds themselves. The Aux port sleeves are removed (not too happy about that, but nothing i have money to deal with currently). But results are purely from the manifold swap.

Might have been different with a functioning VDI.