Not for the "C", at least not that I am aware of and the port spacing on the "L" is supposed to be different.
T'were me, the first thing I would do is to open up that horrible restriction where the oulet pipe is attached to the manifold.
Top picture - as from the factory
Bottom - about 30% more flow area
If that were not enough, the front manifold is not that bad but for the rear I'd look into separating the crossover and the rear manifold and bringing a new pipe down to a collector about a foot or two below the current location. Of course this would also require a new head pipe.