20" lift???

If the coil sags then are still preloading it at the same foot/pounds?

 

Yes, you did, and I was instantly disappointed. Was hoping for a dumpster fire.

 

Technically, if they are sagging, the load is not the same. That would require sagging from them actually being overrated and having lower tensile strength. Like being rated at 580lbs/in and actually being closer to 550lb/in. Resulting in less lift height. But if you compressed them another 1/2" by using a notch the constant load would be 225lb/in more just sitting idle.

 

There is a entire rabbit hole on springs and compression rate that I can't remember all the details of at the moment.
Typically you would get a longer /stiffer spring to achieve the lift. Pre loading the spring is a necessary evil to dial in a specific ride. On the 5100's it's more of a cheat/cheap way to get the truck in the air.

 

https://www.headstrongoffroad.com/store/c147/ADS_Suspension_Kits.html

 

6112s with 1/4 HS Spacer
https://www.shocksurplus.com/products/bilstein-6112-strut-spring-rear-5100-shocks-set-2016-2018-toyota-tacoma-4wd?variant=14602567122993&utm_medium=cpc&utm_source=google&utm_campaign=Google Shopping&gclid=CjwKCAjwscDpBRBnEiwAnQ0HQGsRb0v7y2sRgt6s36SXl9RYJU5vt_tDXCOjC_vzTDGxyvUmNBHH0BoCZ-8QAvD_BwE