I too have questions about this. Working on a showtime with my first four stroke engine(Saito 91). Engine will be covered by the cowl. I have a T-fitting to place in line with the Needle valve to fill....but what about the overflow? Do I also "T" the muffler pressure line? The engine will be almost inverted....Head will face 7/8 o'clock postion. Can I just watch for overflow from muffler? Or will this cause issues starting? Would I be better off using a 3 line system for filling?