Have someone run a water hose over your trunk while you open up the passthru in the center of the rear seat and keep an eye on the inside of the trunk with a flashlight and see where it leaks

 

Just a follow up...so my leak issue has not been resolved with the round 1 patching of the weld directly under the trunk lid seam. As you suggested earlier VQ you were right. My entire rear interior of my car is now living in my basement and I have been able to determine that water is indeed coming in thru thru the windshield. It is traveling down the side of the windshield and getting inside. My deck speakers are shot because of this. I posted pics in a thread I started in the coupe section. Check it out...https://g35driver.com/forums/g35-cou...-05-coupe.html