I PID'd my Silvia and I've found that I can get better results more consistently (but then, I never had the patience for temperature surfing).
If you decide to PID your Silvia, please don't rely solely on Murphy's instructions. You need to get the proper FT1 rated high temperature wire, make sure you use rubber grommets wherever wire passes through sheet metal, and put the recommended fuse in the hot line to the PID.
Although I have no experience with them, the PID kit from
looks pretty well thought out.