I have a cargraphic 3 stage exhaust on mine and tuned ECU. I'm noticing bucket loads of power early on but a tapering off of power in the high rev range.

I don't think there's anything wrong with this, it's just the nature of this car. Larger intercoolers may help with this but there is only one real solution that is not really needed, Bigger turbos.

I guess the more Power we experience, the more we want.

 

I had hardly any lag even before remap. Something quite not right.

 

My 2007 Tip ran a 3.1 0-60mph but it does have many aftermarket improvements.
I also just googled '2007 997 turbo' and Car and Driver's test with a manual reads 0-60 3.6 -3.7 sec. The TIP has a better 0-60 than a manual.

 

Check that your fuel pressure reference line is attached. I had the same problem on my 2007 tip. The symptoms are poor pickup from low revs and engine runs very lean, but no CELs. It's easy to check and fix and a common problem. Plenty of stuff on the Forum on how to check it and fix it.