Adding tweeters to a non tweeter car with a pretty stock system

I am sure this has been asked before, but I can't seem to find anything. I have a very early 02, with no wiring at all for the stock sail tweeters. I bought some, and would like to install them. My question is, on the models that came with them, were the tweeters basically just spliced off from the door speakers? Was there a separate channel on the stock head unit to run them? I have an aftermarket head unit and aftermarket door speakers, all running off the stock wiring. If I add the tweeters to the door speakers it would basically drop the head unit amp to a 2 OHM load correct?

You're fine adding in the tweeters... They use very little power and won't overdrive your amp.

Tweeters often have really high impedance.

Splice them in, in parallel like the diagram.

Aftermarket or stock tweets?

You'll need to put them on a crossover or capacitor. I don't know of the stock units have them built in or not, but aftermarkets probably won't.

They'll sound like ass and won't last long if you try to run them full range.

Stocks. The stocks do have small caps built into them. I have only ever dealt with running component speakers and amps, nothing off the head unit. Trying to just keep it mostly simple. Thanks for the diagram PCB!