300bhp on stock manifold? Good luck with that. They’re on their **** around 275-285 bhp, not to mention the EGT’s.
There’s two ways of doing this. The cheap wrong way or the expensive right way.
You could get away with FMIC, inlet pipe, air filter, downpipe, sports cat, injectors and have 280ish bhp. Stock turbo, no rods. Rod friendly mapping. To be honest you’re gambling abit with rods with this as you’ll be around 300 lbs ft.
After that, you’re pushing things and it gets expensive to do it right. If you want 300 you need to get a manifold, fuel pump, hybrid turbo, rods. With a good hybrid you could be up to 330-350 bhp etc. At the mileage you’re likely at, your valve stem seals are probably ready to be replaced.
You can take the turbo off from underneath but it’s abit of a nightmare. There’s no easy way to get the turbo off unfortunately.
If I were you, I’d either do option 1, the cheapest option for 280ish.
Option 2, the expensive but proper way for 330-350ish
Or push your luck chasing 300 on a stock motor and stock manifold.
We don’t do rods etc for fun it’s necessary. There’s no way to do rods without removing the head either.