Tony you need to at LEAST get a rewired Walbro 255. Not the high pressure one. A 16G needs more fuel. My friend Jon was stuck in the mid 13s on a rewired walbro until he got his 660 injectors. He installed those and dropped to low 12s over night. (all on an RRE Big 16G).
At the least spend the $105 for the pump. Injectors would be extremely wise though too. 650s are the same price as 550s, so go for those instead.