Wheel size needed
 

I'm wanting to get the 5 spoke wheel by Enkei Kojin, what size would I need to fit my Stock hieght Scion FRS? Please help!

Any of them, as long as they're 5x100. I believe they're available between +35 and +45 offset, so really any of them will fit. The 17x9 and 18x9.5 with a +45 offset may rub in the front if you go with super meaty tires (like 255+ width).

The important question here is which tires do you plan on running? If you want to re-use the stock tires, you can run the 17x8 in whatever offset's available.