check chris's build thread. its all in there. i think he took 2/3rds out of the front bump stops... dont know what would happen if you just took the whole thing out? rear is all about playing with flipping leafs around till your happy.
unless your towing or have a heap of stuff in the back, the A12 should do more than enough. give it a good service and a tune. but if you need more then yes, stick with a A series, A14 or A15, but as elemental_funch said watch out rego, and corners as it will now be a rocket. but yeah, have a look at the tech wiki.