Here is what I did with my gen5 34 and it works. Glock Store (SKU 1231) extended tungsten guide rod. Then I got a wolff 10# recoil spring and it pairs perfectly with my 165gr 9mm at a 130ish PF. You can buy several different weight springs an see which one works the best for you.
GS recoil springs are not right. Also, I tried GS new pure tungsten guide rod with no success, you are forced to use their proprietary springs which goes back to my last sentence.
I get accused of shooting "under floor" rounds on occasion. I have on several occasions throughout the last year chronographed them and am always above floor. That's how well the combination works, for me. Oh, and a Thug Plug, that took some fitting with the medium back-strap and TT mag extenders, but that's another story.