some folks have issues with the seals when mounting -- apparently aftermarket seals for VW beetles can help -- this thread (and the myriad of threads linked in it) should help
https://forums.pelicanparts.com/porsche-911-technical-forum/697738-frustration-post-h4-install.html - also, worth considering zip-tying the assemblies in, as a fair # of folks have run over their H4s shortly after mounting. Also, be sure to re-aim once installed.