But shouldn't I go with a s5 because it has the Rad fill cap on the rad and not on the thermostat housing? I have the plastic thermostat housing that came on my s5 engine.

 

I bought a godspeed radiator a little less than a year ago. The quality was fair, wasnt great but for the price it seemed ok. When I finally got around to installing it I ran into a few problems.

First, I have an s4 so I needed to get a pair of s5 brackets. After getting the s5 brackets, I ran into the next problem of the mounting holes on the radiator not lining up with the ones on the brackets. Also the bolts used to mount the stock radiator to the brackets were a different size than the ones needed for the godspeed. Finally after getting the brackets mounted up to the radiator. Go to throw it into the car and run into the next problem of the filler neck being to tall and not allowing the hood to shut.

 

The S4 Koyo has a filler on the radiator (last I checked), which is why I said either will work for you.

 

The "godspeed" radiator I got had the heater return hose nipple welded on the side of the lower radiator hose pipe. I tried to install it in my car, but no avail. That sideways nipple ran right into the frame, and there was no way it'd fit. I tried contacting the company, but no reply. I was stuck with it, but at least it has decent welds that aren't leaking (they definitely don't look like the poo welds that Bamato posted), and it's cooled the car much better than the stocker. Better than paying 2x price for a Koyo. I ended up modifying the car to make the radiator fit. I don't have a tig welder, and was not about to take it to a welding shop to have them charge me the price of my radiator to make it work.

I think that "Godspeed" is just a label that Chinese companies buy to sell their shitty parts. So anyone can make a radiator, buy the godspeed label and sell it as a "Godspeed" part. So you may get a good quality radiator that was made properly, or you may get one made by a 6 year old working for pennies a day.