a slipper clutch should have 9 drive plates in it
and the drive plates when stacked together on there own should measure 22.5mm
if the pack is less than this you should replace one of the 1.5mm steal plates with a 2mm item
you need to work out how many dished plates you have.
there should be a maximum of 4
I run mine with 2
then these need to be placed apposing each other throughout the clutch pack

Not according to the instructions supplied with a DPP strada clutch, it should have 7 3mm drive plates in it..... from all the reading i've done anything from 7 x 3mm, 8 x 2.4 or 9 x 2.4 is possible the DPP instructions say 7 for strada 9 for corsa, I'm not convinced there is a definitive answer to this, try it and see if it works is what I've been doing and have run 9 at times.

the booklet I have with the corse race item says 9
I think the important thing is the depth from the top plain plate to the outer edge of the basket which is suggested to be around 4mm

ive taken a chance and tried it with 9 plates with 3.5mm remaining on centre hub and its not slipping, but feels a bit dry / grippy when pulling away,
will tray swapping over some friction plates for some others that i have and see if that cures it

these should help

they all do that for a while
let it bed in.
they are very grabby on take up

with the risk of embarresing myself here
how do i know the differance between a dished plate and steel plate.
a

they have a dot punched into them
you then place the first with the dot facing you then when you put the next one in the dot should be facing away from you (apposed)
hence the little dot next to C in the picture

ive looked for a dot on the plates but havent seen any with dots. ? perhaps im just not tuned in to what im looking for, where on the plates are the dots?

on the tooth directly under the little semi circle notch