Moor boost means more material and this yiu need to lower the compression a bit by making the bowls bigger and more effective for large nozzles to get to a 300hp #Ok I see and what exactly do you mean by the pistons need machining?
Don’t we all start this way ? It doesn’t make financial sense to modify a engine built with economy in mind but we all like to tart up our cars with go fast bits even if they add zero benefits to the whole recipe ! Making a car cheap, fast and reliable is a bit of a dark art in this day and age however not impossible!!Then another 2k around the engine and another 1k on suspention and 3k on tires. Dont forget wheels, big brake kit, and so on. Soon your car that is only insured for 3k will be worth 13k.
Ita not a smart move financially as you can go get a 310wbhp Subaru WRX for about 5k and put $1500 in tires on the stock wheels and still outperform your tdi in a corner.
And then God forbid engine just explodes and disintegrates, that’s even more money (that you don’t have maybe??) in the hole.This is why I say that if you cant afford the price tag for the parts alone.... you wont be able to handle the total engine cost build to reaches those goals relatively.