How to tune a 1.9 T4 in 2020?

[Gdourado]

Hello, how are you doing?
After some hunting, I am about to finally pull the trigger on my first Volvo.
I am looking at a 1998 S40 T4 with the 1.9 engine.

The car looks to be in good shape, especially for its age.
It has been taken care of and maintained and does not have a very high mileage.

If I do get the car, I will first have it serviced and see if there is anything that needs replacing.

Then, if everything checks out, I will be looking at getting some more extra horses from the engine.

I will not want to open the engine and do a crazy build.
So internals are to remain stock.
Besides down pipe, exhaust, remapping and maybe either a bigger turbo or a hybrid stock one, I would not be looking at doing much more.

I find some information about mods and tuning for these cars, but most of it is from around 2005 or 2006. And we all know that engine tuning has come a long way since then.

So I am looking if there are some upgrades and some guides that are more current and up to date on what to do the engine while remaking on stock internal to get a good and reliable power boost.

Also, how are the stock brakes and suspension?
And does the gearbox hold up to more power?
Are there any LSD units that are plug and play from other models? Or is an aftermarket one like a Quaife the only option?

Thank you for your help.
Best regards