my 3.3 in my slayer has also seen temps of around 300. as long as you shut it off immediately and let it cool and then richen it and try again it shouldn't hurt it. at least that's what the guy from traxxas told me when i called. you just don't want to keep running it at 300.

mine usually runs great around 210 at about 4 1/2 turns on HSN which is a little on the rich side for me but i'd rather be a tad rich than too lean.

i also run pretty rich on the LSN also. i'll richen the LSN up until it will sit and idle good and not bog on acceleration.