The best way I have found to improve shifting is with a b&m trans pak for sale at most auto centers.Its fairly easy to install and comes with full instructions.you can modify the trans yourself without the kit but if ya dont know what yer doin,well you can figure that out.Anyway the trans pak comes in 3 stages.They are about $30 to $50 depending on where you live.Happy shifting.

What exactly is it ? How is it installed and does it lower the life of the transmission ?

Well its a new set of gaskets and checkballs that you place at specific points in the valve body.It instalsby removing the trans pan and valve body and following the instructions,which are fairly clear and can be done on a Saturday with basic hand tools.I really is easyer than it seams.And it actually extends the tranny life by not allowing the tranny to hesitate between shifts.When a trans takes longer to shift it wears more.Not to mention it keeps the revs up which is a good thing at the track:)Hope this helps.