Removed the lower cowl and reattached the exhaust. Used a vacuum cleaner tube inside the exhaust to find the extended center of the pipe and marked on the floor. Taped a laser level to an angle level and positioned on the floor mark so that the pointer went up the center of the pipe. Made reference marks on the floor so pointer/level combo could be reset. Removed the exhaust and reinstalled the bottom cowl. Restored the pointer/level combo and marked where the beam intersected the cowl. Cut a hole in the cowl a little larger than the exhaust pipe. The result was good enough for a test fit with the exhaust attached. Marked where additional trimming was needed and repeated thim/test fit until I liked the result.
Finally, I made 2 cuts in the bottom of the scoop and folded the bottom up so more air would be directed towards the airbox. It is held in place now with clecos, but will be cleaned up when I do the fiberglass work down the road.