what should I make?
#16
You didn't say Jun, though. Jun is on a whole different level, but they are way aggressive and not designed to work with the stock ECU/MAF or even the stock turbo. There's not a huge difference in GSC 272 and HKS 272. You are asking a question based on what you remember of what someone told you who was told something by someone else without fully understanding the situation - doesn't do you much good.
#18
There's a difference in EVERY cam, otherwise there would only be one choice. There is also no such thing as a JUN 280. But the bottom line is, a more aggresive cam will only get you more power as long as you have all of the proper parts surrounding it, otherwise, it will just make your car idle worse.
#20
In fact, the HKS 264 has 0.2mm HIGHER lift and 3* MORE effective duration than the GSC 272. The HKS 272 has 0.2mm HIGHER lift and 11* MORE effective duration than the GSC 272.
But you have to take that with a grain of salt. I do not have lobe centerline info on the GSC, nor do I have lobe shape information on either. We haven't even discussed lobe shapes. The actual lobe shape can have just as much impact as lift and duration. Keep in mind that lift and duration are (for lack of a better term) a measure of minimum and maximum lift. How quickly the cam goes from minimum to maximum lift will impact both performance and valvetrain load.
Then, once you know all of this, you have to see how each of these aspects will interact with the parts on YOUR car. Anything major like oversized valves, ported head, ported intake or exhaust manifold, stroker kit, or a bigger turbo will have a drastic impact on which cams are the best for your application. And unless you have access to computer modeling programs and a vast database of knowledge, you'd be better off just asking someone. Or for that matter, cams aren't really that expensive, just buy 2 or 3 sets and dyno all of them on the same day.
So to answer your question, it is possible that the GSC 272 cams could make more power than the HKS 264's on the same car, and possible, but not likely that they could outperform an HKS 272.