LS9698

I bought an '05 LS with the sport suspension package last week 75k miles. It has the 18" chrome factory wheels and Michelin 245/45 R18s. The ride isn't ridged and stiff like I was expecting, it's quite smooth and rides like a luxury car but corners and lane changes like crazy.

I gave my 96 LS to my brother and kept my 98 LS.

The handling on the 05 is so great that when I drive the 98 I now want that same feel. The cornering on the 98 feels like a boat now.

My question is where to start determining which spring's I can put on the 98 and recreate the amazing handling of the 05. And any other suspension parts that could help.
Like sway bar thickness.

I'm no stranger to replacing suspension parts, I replaced every single part on the front of the 96LS.

Thanks in advance.