I recently had my car mapped by K-Tec along with a decat and K-Tec Exhaust.
My car Dyno'd at 185bhp pre-map and 199.4 post modifications.
I don't think it feels aggressively faster, but more...urgent. However, I have a jap loving mate who continuously gives me grief about his silly Civic Type R.
Pre-Remap drag to 100Mph (private land officer) and we are talking about him beating me by about 2 car and a halves length, most of which the CTR made up after 60mph
Post remap....and I beat him by about the same distance!!! Woooo Eat sh*t and die Dan, you got owned by a garlic baguette lover you son of a rapist...
Now i know it's not scientific and there are other factors to bring into play but that was enough of a difference for me to be very happy.
The exhaust sounds too good too, nothing like pop's on gear change and a lovely fruity tone when you get her revved up.
So boys and Girls, Decat, Cat-Back and Remap in my opinion are well worth the pennies.