LSI is just a marketing gimmick. People get more for a designation and the rights to earn bragging rights by showing to everybody what model they have.
In the beginning they had a standard meaning, like S for Sport, SS Super Sport, GS for Grand Sport, L for Luxury, LT Luxury Touring or Limited, LE for Limited Edition, R for Racing, I for some that was Fuel Injected and so on.
So LSI could mean Luxury, Sport, Injected.
Now days is more kind of pointless since no manufacturer follows that protocol. One thing is true, the more letters and numbers the more comfort creatures and higher price tag.