[Formulajones]

You can somewhat tailor that with an adjustable vacuum modulator. Most of these cars over the years have already had one installed as that's what is readily available in the aftermarket.

If so, it's just a matter of removing the vacuum line on the modulator and with a very tiny screw driver you can turn the screw in (clockwise) to increase the shift points, and counterclockwise to lower them.

Increasing the shift points spreads them out a bit and will increase the firmness slightly as it now takes more vacuum to overtake the diaphragm. These adjustable units are also affected by elevation, as higher elevations will increase the shifts where engines make less vacuum, and lower elevations with more vacuum decrease the shifts. So depending on where you are located or where you drive the car will have an affect.