Best ifs kit? rms, hdk, gt suspension, or magnum force?

I forgot you are planning on racing ........so maybe (?????) you will need all those springs.

For a street car......stick to the basics....unless you want it to ride like a dump truck. (famous Bob quote from post above). From experience, BOTH too light and too hard on coil spring selection can cause the dump truck effect.

The spring simply holds up the car, As stated above, the 25% to 33% spring collapse is the range you want to be in.....there will NOT be several rates that fall into that catagory.

The ADJUSTABLE coil over shock is the way to tune the ride.....that is what that little knob(s) on the base are for.

BTW....I will bet most can change out torsion bars as fast or faster than they can change out springs (installed in the car).