Hey Phsyco,
Lowering springs and struts are always a great upgrade. You can do some engine performance bolt ons, but the yield is marginal at best. There are several articles out there about built supercharged/turbo v6 cars and this is definately the way to go unless you want to do a V8 swap. To be honest it all comes down to what you want to get out of the car. A V6 SN95 will not be a fast car compared to a V8 version. However, it is your car and you should be proud of it. I would focus on handling and perhaps a conservative exhaust that has a good sound.