As ive been there and done it before several times, there are many things to think about, like whats the best decision to go. Everyone's got different decisions and budgets to follow.
As you do have an Auto, your choices are limited.
As a powerdyne is the lowest form of sidemount blower, at low engine rpm's i think you will be disappointed, for example 3 psi at 3000rpm, is plain boring. And at higher engine rpm total of 5-6psi so you will net very low power figures. Basically the same as a cammed ls1.
However as you do have an A4 you will need a stall to match the camshaft, so dont forget about this when working out a quote.
Power figures and price......these are approx power figures on the mainline dyno, none of these prices are with exhaust mods etc etc.
LS1 with Powerdyne Blower 285rwkw ($7000 fitted, tuned, map sensor & injectors)
LS1 with NOS Shot only 315rwkw+ depending on shot size ($4000 fitted, tuned, injectors and pump)
LS1 with camshaft & NOS 350-400+rwkw once again depending on size.
($9000 cam install, fuel system, injectors, fitted and tuned)
So personally i know what i would be doing.