I absolutely love this case and it was a breeze to work with in terms of an ITX case. This was my first computer build and everything worked out fine. Shout-out to the friendly community of the PcPartsPicker and LinusTechTips Forum for answering my little questions.
Build Part 1 - Putting it together The first time I put this together, It did not have the AIO cooler for the GPU and the Noctua Fans. There was plenty of room to place in the MB and everything that connected to it. The ASUS 1080 STRIX has a large 3 fan + heatsink set up on it, which lead to very little clearance for air to get into those fans. The surface of the GPU to the Power Supply shroud was <1 cm. The AIO for the CPU was easy to install and I first had it as an intake in the front. The Manta comes with a nice dust cover for this.
Build Part 1 - Performance The PC performed beautifully and I could run games at extremely high FPS while gaming on Ultra on a 2k, 144 hz Monitor. The one draw back was the GPU temperatures would sometimes spike to ~80C during intense loads and the tripple 80 mm fans in the ASUS 1080 STRIX are quite loud. So that is when I decided to add the GPU block and the Noctua Fans to reduce temperatures and minimize fan sounds.
Build Part 2 - Upgrade The AIO for the CPU was moved to an exhaust at the top of the case with dual 140mm fans in a push orientation. I did this to allow for more flex in the tubing lines because the tubing lines come down right on the rear 120 mm fan I have for exhaust as well (Swapped the stock 120 mm for a white one I had laying around). The AIO for the GPU had its rad in the front of the case with Four 140 mm fans in Push-Pull Config. I should be known reaching the screws for all these fans became a nightmare so be warned... But if you're resourceful / determined enough, you'll figure out a way. I would prefer to have the Rad's switched (with respect to CPU and GPU), but due to the preset tube length and the location of where it connects to the Radiator, it would simply not work in this Case. But in reality, the temperatures are nothing to complain about.
Final Comments I also upgraded the rear 120 mm fan with something a little more powerful (Noctua Industrial Fan), but it had no real impact on temperatures. So don't waste your time.
I was surprised that I could fit all the cables I needed for this. Needless to say the Manta has PLENTY of space for all your needs.
I also added some Sleeved white cables and 2 LED strips to spice it up :D