Getting good airflow can be lots of fun. I agree with Splitframe, flip the fans. Pull air in with the GPU fan and exhaust it with the Noctuas. Your tempratures should improve. Speaking of tempratures, can you give us some numbers? I'm curious about the performance with and without the Noctuas. I good test is to measure the max temperature after 3 runs of Unigine. You can use a GPU overclocking tool (MSI Afterburner, etc..) to get fan speed and temperature measurements.
I would love to know the temps, with and without added fans. Thank you.
Oh, and so happy to see these modifications! Nice work.