A couple thoughts on this.
First the guy with GT/CS was only giving you a seat-of-the-pants review. Which should should only be taken with a grain of salt unless he has a dyno graph to back it up.
Some people are just more receptive to changes in a cars performance than others. Personally, I notice improvements from my mods, but I also become used to them very quickly and forget what the car used to feel like. For instance, my car is way faster than it was bone stock, but I am so used to it now that it feels like it did the day I first took it for a test drive. I am easily around 310-315 rwhp at this point.
The second comment I have, is on the guy who has a Mach 1 and only gained 6 rwhp. Well, we are talking about a SN95 Mach 1, not a S197 GT. Machs have an entirely different computer system, heads, intake, and are DOHC. From what I understand the N/A DOHCs didn't really respond all that well to minor mods like a CAI. They flow well to begin with.
Third, about half the gain from a CAI package on a S197 is from the tune. If all you do is tune your car, you can get about 10 rwhp from that alone. Then you add the CAI for about 10 more. Bamachips/Brenspeed mail order tune/CAI packages will put you at 285 rwhp, which is about 20-25 rwhp over stock.
So the bottom line is that you will end up in double digits in performance. I went with a JLT2 instead of the C&L mostly because of the cost, but the C&L looks great.