The ornamental design for an exhaustmanifold, as shown and described.
FIG. 1 is a perspective view of an exhaust manifold showing our new design;
FIG. 2 is a second perspective view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a rear view thereof;
FIG. 5 is a top view thereof;
FIG. 6 is a bottom view thereof;
FIG. 7 is a right side view thereof; and,
FIG. 8 is a left side view thereof.
The drawings include gray-scale shading which represents contour, not surface ornamentation or any particular color. The drawings include shadows and reflections that form no part of the claimed design. The broken lines indicate boundaries of the claimed design and form no part thereof; the white areas within the broken lines also form no part of the claimed design.