Law / What car modifications can be performed on a car registered in Poland? [6]

Hello,

Since lot of cars get modified here in Poland, I'd like to know if the car I purchase is legal or no.
In details:
1. Can the engine be swapped without limitations?
2. If no, can the engine be swapped for another one from the same car model but with different size/capacity/power? For example, the engine from a mercedes w203 c230 into a mercedes w203 c200

3. Can any other mechanical part be swapped? Like take a transmission or a differential from a thir party car parts builder company and put it into the car.

4. If no, can it be done using the original car manufacturer's parts?
5. Can the front/rear bumpers and sideskirts be swapped using non original parts?

I'm a little concerned because there are lot and lot of old cars that may have been modified with stuffs that in my country of origin are considered illegal, so I don't really want to have trouble with insurance or yearly car inspection.

I know these are not easy questions to answer but my limited polish language skills don't allow me to get all the informations I'd like on polish law.

So thanks in advance for any answer.

Law / New car registration with old insurance after car purchase in Poland [5]

Hello forum,

This is my first post here,

I recently bought an old beater car, it's insured with basic OC to the precedent owner till June 2019, but he was paying that in rates every 3 months, so it will need to be renewed in January and April.

1 - Do I need to register the car at my name or can I drive it without registering it? Talking with a guy he told me that I don't need to register the car again and that the purchase contract was enough to drive, but reading online it looks like I have the obligation to register it within 30 days from the moment I sign the contract.

2 - Do I need to cancel the current insurance and register one at my name? I'm a young driver and the current car insurance is considerably lower than the quotes I got around the internet, so for me it would be nice to just renew the current insurance till June, but can I do that? I really don't want to get in trouble with insurance refusing to pay because the insurance was not at my name.

Thanks in advance for any help.