Depends on your goals and budget.
C/F Hood, C/F trunk or hatch, C/F front and rear facia, Lexan windows, Lightweight wheels, Alluminum rotors, light weight gears, All. driveshaft, All. flywheel, smaller fuel cell, All. block, K-member + A-arms, Lightweight seats, Interior delete, total A/C delete, Flaming River Manual steering rack, Removed front and rear bumper (the under bumper, not the cover facia), Smaller battery relocated to trunk or pass. side rear floor,
If its a fox pry up the sound dedning gabage glued to the metal on the inside floor.
To go extreme fiberglass or C/F doors.
After that its being creative like side wiew mirror delete, wiper delete, removing side skirts and fender well plastic, sand the car down to bare metal and use 1 coat of white primer.
I know this is very excesive but im not sure how deep into race you are going, some times you need every ounce gone. But those guys usually start with a bare chasis and only put on the necesitys.
Also if you are looking for even more time get a girl that weighs like 115lbs to drive. And when she spanks people will freak that a girl was driving. And tell her not to eat for like 2 days before the race. harhar