I tryied to find this suff and could not.

About how much does a 99 z28 weight with t-tops and A4 loaded?

Also what does line pressure do in a tranny?

 

Find the nearest truck stop and use their scales.It costs like $5 and you can get the weight of YOUR car since no 2 are exactly alike.

It tells the tranny how smooth or how hard to shift between gears.More line pressure equals firmer shifts.That's how the HPP 3 changes the shift settings.
Kevin