a15s are great, i had an a15 in my car which had been rebuilt and had a nice "street" cam installed, using a 32/36 weber, extractors and thermo fan, this kept up with the latest 6cyl commodore (VY), i dunno if you get many commodores there? i guess you would

im currently building a turbo setup for it now, should be finished quite soon, im running twin turbos in a blow through setup, at first with a 32.36 carb running 7psi, but plan is to inject lower comp and up boost as soon as i can afford

im leaving the bottom end stock contrary to what most tell me, but i have faith in the old a-series, i spose ill find out pretty quick if i over do it

it is quite expensive to setup a turbo system, but i couldnt really give a cost, as there is so many variables in how to set it up, i feel i have done it properly this time aside from the bottom end, and its cost me packets for all the bits and pieces, but i have saved a lot by doing it slowly and collecting up the bits i need over time when they come up cheap sorta thing

best of all i have learnt HEAPS along the way, and thats something ive really enjoyed about it