SS-AFC is an air-fuel controller made by Split Second, there are a few retailers that sell them new and they pop up used every once in a while. Be sure you get the correct AFC for the MSP, part number is PSC-020E IIRC. For a reliable 250 whp you will need a forged motor in my opinion. If you are fine with risking the stock block go for it.
agreed, 250whp may be attainable on the stock bottom end, but it definitely wont last long.
I'm not a fan of the CX racing MSP FMIC kit due to how excessively long the pipe routing is. In my opinion you can build yourself a better setup with CX racing's universal kit for less than half the cost of their MSP one.