If you want 400kw from the FG it won't be some simple mods - you'll need a new turbo to start with (FG's have a smaller turbo that has it's balls at the lower end, not the upper - the older ones had longer legs, but didn't get up to speed as quick) Work out what you want from the car rather than a number - chase the outcome rather than a dyno figure If it's a long term goal to get to 400 then find a tuner you can trust and work with them towards building towards that. Make sure you only pay once for items - each thing you change will require a tune, but each item you replace will require a tune plus the full cost of the correct part. Stage your changes so you only buy parts that won't have to be replaced the next step up. 400kws done wrong may cost you a transmission, turbo, tailshaft, engine and a lot of money - done correctly it could fall within your budget (if you budget correctly). If you just want the first step now - then probably a reputable tuner for a flash tune would be the way to go. Get one that will make sure you have the right pipes/support for it, or that will suggest what changes are needed for them to be comfortable to perform the work.