Do a bit of research on this forum. HEAPS of different paths have been taken in reguards to sucking all the potential power out of a A series.

How much power is more? Do you want to blow away new 6ltr V8s? Do you want nice reliable punch when you need it? Do you just want to be able to keep up with traffic?

What is your budget. Sure ideas of superchargers and turbos are nice but can ve very expencive and unreliable at the best of times! And remember you will have to upgrade your suspension,brakes,diff,gearbox while you at it!