There's a wealth of technical info and 'How To' articles on our sister site at
www.gtfours.co.uk There's even detailed info on spark plugs:
http://www.gtfours.co.uk/what/colder_pl ... _plugs.htmIf it's not already running Toyota ForLife red coolant in the engine and charge cooler I would drain and change over to that. It's anti-corrosion qualities seem to be superior to anything else. This is a collective view, not just my own experience.
One point I did pick up in your other thread on the Greetings section are the braided brake lines. On the ST205 fitting braided brake lines to the front superstrut suspension is quite tricky as the routing is critical to avoid stressing the lines with the strut's arc of movement. I've seen quite a few failures on different makes of braided lines. Might be worth checking.
One word of caution, if you are planning on raising the boost then the OEM pistons which are of the hypereutectic type (not forged) can experience ringland failure due to detonation. You might get away with it as your engine is low mileage. On my 300bhp ST205 I ran a 50:50 water/methanol injection to keep air charge temps down in the plenum. If this airlocks or fails then you can det the engine and break the ringlands. Eventually this happened to me on track day at Buntingthorpe.