Originally Posted by andy-mu
By remap I presume you mean chipping. From what I've seen, that would appear only to add about 20 Bhp. Is that really worth it. I know with other makes, chipping can mean new gearboxes and a whole list of other perfomance upgrades. Can you just remap? excuse my ignorance on this one.
Nope, he means remapping - having a professional tuner write a new ignition and fuelling map onto the cars current ECU. Chipping is fitting a chip with different ignition and fuelling maps to the car, you don't need to do this on newer cars.
On a normally aspirated petrol engine you are unlikely to see even 10bhp, nevermind 20bhp, but its the increased smoothness and responsiveness that makes it worthwhile, plus maybe 10-15 NM of torque from 1,000 to 5,500rpm or so. Free up the air intake and exhaust and then get it remapped for bigger gains at the top end of the rev range.
Unlikely you'll ever need to do anything with the gearbox though.