When ever ive changed pads in the past ive always found that they were previously fitted with a dollop of copper slip on the back.
Would doing this with the powerlites be advisable seeing as they dont have dust seals
or will it be ok as long as i make sure i clean the pistons before pushing them back in?

The copper grease is usually put on the back of the pads to help stop squealing. It should be ok on your Wilwood calipers - as you say, just clean the piston before you push them back in

[Edited on 4-9-06 by RazMan]

Copperslip antiseize is used to help prevent squealing. It is a petroleum product and rubber hates it. We use a high temp silicone lubricant at work instead. You need that stuff for caliper pins and any rubber/metal contact anyhow.

Cheers.