It depends on what springs you got from AP. They used to use USA made springs back when I was working there and those were great. Then they had the same springs made in Mexico. That's when the complaints started coming in with springs sagging and breaking. They had far fewer problems with the US made springs. Now the springs AP sell are made in India. I've tested springs from the same plant and we are not happy with their ability to retain their lift.
It kills me to have to charge a higher price than our competitors like AP. I want to offer good products at the best prices. When we first started making springs our prototypes were made in the US for faster delivery so we could test and change them fast. After a couple of changes we had what we wanted. Our supplier promised us that the Mexico springs would perform exactly the same as our prototypes so we went with springs made in Mexico to keep the prices low. The springs came in and with our prices similar to AP we sold them all in just a few weeks. But then we had some issues come up and a few trucks really loosing a lot of lift is a short time even with bumpstops installed. We took a set and put them on Dave's truck. Dave had the 4" USA made prototypes still on his truck and still working like new. So with the Mexico springs on Dave's truck he drove through the Dusy trail just like he had done with the USA springs. We noticed a huge difference when he got back, the USA springs had not lost lift but the Mexico springs lost a bunch of lift, about 2" and the front of his truck was much lower than the rear. We called Betts springs and sent samples back for testing. They kept saying that they were the same as the US made springs. After those 50 sets we never bought any more Mexico Made springs and every set from then on were made in the US plant. We have now sold more than a thousand pairs and only had a couple of returns from unhappy users.
We know that we must offer a low cost springs to stay competitive so we have been testing sample springs from Canada, Japan, China, India and the USA to find lower cost quality springs for the future.
As to your question about your springs. It seems that just about every truck leans a little bit one way or the other no matter who's springs you use. It's not uncommon to be off by an inch or more. If it is enough to bother you there are a few things you can try to fix it. First is to swap the front springs left and right. Then drive the truck a bit and check to see if that fixed it. If not, swap the rear springs left and right. Sometimes the rear springs can have more to do with how lever the truck sits because the rear springs are further out of the axle than the front springs. If the truck is still not level you can play with welding spring pads onto the housing (front and/or rear). A spring pad that is 3/8" high can make a difference of 3/4" up front. I would not use more than 1/2" of pad. You could also try adding a short leaf to one of the springs to give it a little more lift on one side.
Bumpstops are key. We usually test our springs without bumpstops as it allows us to age the springs faster. Installing bumpstops keeps the springs from bending too far and loosing their lift. Typical gap would be 3"-4".
