Check with a company call Bell tech. I have lowered two pickups in the past with their lowering kits, but they were not Toyota trucks. From what i've seen 2 to 4 inches is usually an easy drop, more than that and you can start having driveline issues and more. My last drop was 2 inches in the front and 3.5 rear, it was cheap and easy, zero issues. Some trucks use a block under the rear leafs, if you just pull those out it will drop the rear some, but does nothing for the front obviously. Check your shock travel as well, because if you lower the shocks themselves can bottom out, either breaking the actual shock, or busting the shock mounts off. I had to replace the shocks on one truck I lowered with physically shorter shocks, because the shocks bottomed out before the suspension did.