Shown in both pictures above:  Top Flite GS kit - other kit contents vary based on specific kit needs

In the picture of Mark Willey's manifolds above, note the cast relief around the base of each stack that creates the illusion that the shrouds are stamped stainless steel.

Each kit has everything needed to install the exhaust system except paint and adhesives.  Included are a pair of precisely cast resin shrouds, 12 pre cut brass exhaust stacks, a paint mask, aluminum foil for creating the stack tip bands and illustrated instructions.  Where needed mounting jigs are included and / or detailed drawings are supplied.

The holes in the shrouds for the stacks are precisely cast so that they position the stacks at exactly the correct angle, both downward and aft.  Stops at the base of each socket set all the stacks at the correct height.  All this and the shrouds are pre-shaped as well.  All the builder has to do is fit the shrouds to his cowl, then detail and paint the stacks and shrouds - that's the fun part and fully explained in the instructions.

The basic design of the shrouds allows them to be mounted on the cowl surface, providing excellent realism with the least amount of work, or flush mounted - more work, but the ultimate in realism.  (Flush mounting requires some clearance inside cowl and normally works best on fiberglass cowls.)

The point is the hard work is already done!