OK, I sold my '87 1/2ton burb, and am now planning the buildup for my '91 V2500 burb. The ride is incredibly stiff (I think one of the POs put add a leafs and made it worse), so instead of keeping the 3/4ton springs and doing a ORD shackle flip or blocks, I'd like to replace the rear springs with 4" TC rear springs. I'm worried that this will affect my towing capacity though, so I thought I'd plan on adding rear air lift helpers, these Air Lift Super Duty Air Springs. Will they help enough to make up the difference between the 3/4ton springs and the TC springs? Do I need the air springs at all? Will the air bags effect off road flex if they're aired down? I plan on hauling a loaded heavy toy hauler in the future (around 9K), so I don't want to do anything now that will make that difficult/impossible then. Thanks for any and all info.