It depends on how you will use the car, if you're not going to be using the top end a lot it might not be worth it just to give a higher peak number. If you're going to give it some fairly often then it will improve that side of things.

I don't know the specifics of the car but in general you'll lose some torque at the low end and gain power higher up and a higher peak power and rpm limit.

Also, some manufacturers recommended you uprate the springs as well, (I think) Piper do... but Newman say don't if it's not necessary.