G'day Haynzy, my personal experience only, I'm now taking next steps with my NA and saving up for forced induction. I'm not saying mines a slug or anything and in fact most of its use is for very slow low down grunt which it has plenty of as is. It is my belief that forced induction is going to save me fuel and reduce heat when it is used on the highway at 2000+ RPM. I'm currently looking at this option below:
http://www.bulletcars.com/supercharg...er-system.html
They are Aussie based in QLD and were recommended to me from a bloke whilst in the USA last year and should suit my low&high RPM needs.
In summary; mine (custom extra cab like ET's) was $30k + $3.5k cooling mods + upcoming charger at $6k + turbo spec injectors. So I'm staring down the barrel of $40k+ when ET got his with turbo and all setup for only $25k drive away :-)!