Only two or three places in the UK who can uprev zeds. Uprev is the remap licence. One is Horsham Developments, other is Abbey. Not sure who third is by I think they're near Leeds.
Abbey are the best. Don't bother doing it now. Wait til you change the exhaust, install a plenum spacer, change air filters. Then do the remap. Maybe even go for decats or high flow cats (HFCs)
Any chance I could come see what your pillar looks like? Really been looking at this recently (hence some of my knowledge) and I'd like to see the finish 1st hand as opposed to on a video/picture.
Can be done and can give great results. However your car paint needs to be prepped very well. I'd suggest full clay and wax job. Any dents/scratches need to be sorted. They can show through. You need about 5 layers. Uses about 3-4 us gallons (14~litres).
Go on YouTube and search for Dipyourcar.com whole car.