I have a set of these heads for my 347. I called AFR today regarding upgrading my springs for a larger cam or 1.7's. He said the stock springs are good for .550. My cam is at .542 and he said he recommended changing them. However he said that they charge around $180 when you purchase heads because they change to a different spring also. He said that if I were to buy the parts now it would cost me over $400 and that I was on my own. What is the deal with that? Has anyone ever changed the springs without the hassle and the hefty price tag?