yeah what he said about the collinear gains is pretty accurate, dont expect miracles from stepping up in collinears if you already have the x50. i tried the gp-9 and it was fine but nothing that made me go wow. one thing nobody mentions enough is coax loss at those frequencies. if you're running like 50 or 75 feet of rg8x up to your antenna you're eating a significant chunk of whatever gain you think you're getting. worth calculating that before you spend money on a new antenna honestly. lmr400 or hardline makes a bigger differnce than people expect.