Well, since the exhaust comes out of the pipes at the rear of your car, to smell it....you'd need to be driving in reverse.
Are you driving backwards?
Leaking onto the top of the LIM usually means the coolant/oil is seeping up the threads of a bolt. Using GM Pipe Sealant with PTFE or an equivalent on the LIM bolts when installing would keep this from happening again.
Being that you see it at an injector boss, it is also possible that the fluid is coming over over the edge of the LIM by the head and then leaking down in, or you have a leaking valve cover gasket. A valve cover gasket would mean oil and oil could be leaking on to your exhaust and choking you to death in the car while driving normally. Driving backwards would not smell.
