Nice collection there. Would like to hear your feedback on the springs as they are on my watch list.
Not sure to do the springs and keep skyhook or chop them entirely out for KW coilovers... Another option is just stick in a new set of OEM springs as it would still offer a significant improvement over 17 year old springs with slight surface corrosion. I already have the FD anti roll bar kit which is a very good upgrade but it really highlights the fact that the springs are too soft and as a result often kicks the back end out on cold tyres/roads so I have to drive it with my finger tips in such conditions... I have been advised to upgrade the springs or shocks to make it more stable
I have Bosch S5 which I got for just under £100 four years ago from ECP during a "flash sale". If I was in the market now I'd go with
@midlifecrisis recommendation. Also love the tip of selotaping the reciept to the battery... I kept mine in the service folder for the car