Then why do all pro springs sag and the trail gear ones dont have any complaints of sag?

That's pretty funny. I read tons of comments on how trail gears sag because of the import steel they're made of. From my understanding, other countries don't control the process of making the steel as closely as America does (big suprise here). Hence, the import springs don't last as long, break easier, et cetera. If you plan on wheeling for many years to come with your truck, just cough up the extra dough and buy marlin American made springs. I think the American made all poo and marlin springs are the same (from what I've read at least) as they both come from betts, but whether this is true or not, marlin is the man and you should buy his product.