GSR Remap and induction alone will take you to about 70bhp which does make a nice difference - 3rd gear is loads of fun! The car goes from being underpowered to more typical levels of performance. I would highly recommend it. Fuel economy is much better too.
I have got a new cam and flowed head which don't really whack up the bhp figures as much as you'd think, as there is a bottleneck with the cat / manifold (basically they are rubbish and in worst possible position) and the throttle body is a tad small. But it is very drivable and as you can see from the graph, the torque hangs in there for ages!
Performance wise I'm keeping up with my dads 1.8 Vectra so it's not slow. My car is a bit of a chav.. may not be hard as nails, but definitely will have a go at anything and make alot of noise doing it

Great fun.