Run highest octane you can get your hands on.
If you're up on maintenance.... have you done a coolant pressure test lately?
I doubt your LIM gaskets are still holding.
Changed the coolant elbows?
Hows the suspension?
You say new GTP yet you have a GT....
Very different motors.
$80 limit? Save your money.
You'll need it when one of your wheel bearings goes or you hit something and need a new LCA/ knuckle/ axle/tie rod.
Hell thats almost a tank a gas.![]()