I have a random "universal" intercooler of eBay on mine, nothing wrong with it whatsoever. Most of the cores (if I remember correctly) excluding the Greddy one and a couple of others are most likely just shitty cores made in China anyway. I'd be more worried about the piping personally, it's something that you have to get spot on and unless you're handy at working with metal I doubt it would be very easy to make a perfect route to the FMIC with that. I may be wrong, and you may strike lucky with it or something, but I'd personally rather just buy a kit.