400 hp

So my previous cars have all been american muscle i have had a few stangs and worked on my dads old charger (71 for those wondering) but i got a sweet deal on a b6 a4 1.8t picked it up for 8500 with 92000 but its really lame power wise.What turbo would you guys recommend to get up in the 400 hp range. I realizes rods have to be changed so im probably just going to do a complete overhaul on the block, but injector wise a was thinking 630cc with a cast manifold forged internals and polished head. Im also at a loss for some software is there a piggyback unit i can purchase or is it gonna be a brandy new stand alone that i will need. any advice would help.