To be completely honest. When both were cooling like they should there isnt much of a difference in performance accelleration wise. On a different note. the 3.5" ETS heat soaked just as fast if not faster than the stocker. It seemed to cool down faster than stock once moving but doesnt even compare to the fmic. The fmic never heat soaked. On a hot summer day with the car idling for a while it was nothing to see 200 degree bat's on the stock or the ets. With the fmic the highest I have ever seen was around 155 or so. But once you get moving it easily would drop down and much faster than the tmic.
Another thing to consider which I was skeptical about is ptp's intake manifold spacer. this was a big drop in temps even with the fmic on. Before when you touched the IM by hand after a drive it would burn my fingers. After the spacer the IM was either warm or cool but not enough that burned my hand without one. The downside to the spacer is the EGR tube cant seem to fit with the IM sitting out 1/4" more than what it is. So I had no choice but to do an EGR delete.
I'd say definetly go for the FMIC. I do not regret it at all. Install is kinda a pain if its a custom kit. But you can have all piping, couplers, clamps, and intercooler for just around 500 bucks. And it will cool better than the aftermarket kits for our cars. Since those tend to sit behind the crash bar.
what IC are you talking about?