Exhaust, yes, but I havent sealed up the rest of the engine.  kinda scared to rip into it...its funny tho, I'll pull a VW engine apart, but I'm afraid to open a little 2stroke lol  I do suppose, tho, its only got like5 moving parts, so, it wouldnt be too hard to figure out where things went.  I guess I could just apply from the outside, but that looks kinda unprofessional vs. a thinly lain bead on the sole contact surfaces.