After probably a dozen rounds of tearing my car apart I can finally say I have fixed my leaks. It's been winter here and everything is frozen so I couldn't use a hose for testing. It has purely been try something, wait for rain, try something else. The main one in the trunk area was the hardest to solve. I would always get water in one corner of the trunk, right behind the passenger tail light.

Leak area in trunk
I tried using RTV on all the grommets in the area, I made a gasket for behind the tail lights and the lifter base, and finally found the leak under the trim on the roof. I didn't think to check there first because the car is a 2017 and thought it was too new to have a seam crack.

Crack under roof trim
After throwing some RTV on the crack the problem is solved!
The issue in the front turned out to be my hood release cable allowing water to run down the cable and through the grommet into the cabin. I threw some RTV around the cable where it goes into the grommet and problem solved. My car also didn't come with wheel liners in the front so I plan to add those soon which should also help to eliminate the issue. I just wanted to make this post in the hopes of helping someone else avoid having to go through the trouble that I went through. It took a lot of time and effort to get these problems resolved but I have a much more intimate understanding on how my car works now so in the long run it was worth it.

 

Congratulations!

 

how do you get roof trim off....goood info, i gave up on my 97 prelude and drilled 2 holes to let the water back out!!!

 

 

this is hilarious ^

Congrats on the fix! Thanks for posting

 

During a long-ago summer wildlife biology job I (+ others) lived in a couple of dilapidated camping trailers. All leaked a bit, and one leaked aggressively. We tried all sorts of caulks and sealants and nothing worked. Finally one of the other technicians got fed up, grabbed a cordless drill and 1/2-inch bit, and started punching holes in the floor where the water was pooled.

I won't say the problem was solved, but the burbling sound of the water draining through the floor was quite relaxing at night.

 

Now that you have found out what it was, you should buy some seam sealer and replace the RTV, since the RTV will cause the metal to corrode.... Just a suggestion

 

I had no idea that was an issue! I would've just used seam sealer from the start if I would have known. Thank you for the info, I'll be replacing it as soon as it warms up.

 

Further info on RTV corrosion:

RTV corrosion

 

Ok, I used ultra black so it sounds like I'll be ok.