130bhp for a stock G40 at Aldon might be a bit excessive (though didn't Nick's old one put that out?), but we're not comparing apples with apples here...
140bhp for 9:1 CR 1341cc with a custom chip, and 123bhp for an 8:1 CR 1272cc with VW's original chip. If you tweaked the map in the stock car to make it a fairer comparison you'd probably get a few more bhp out of it.
Dependant on spec and tune it's probably something like a 5-8% increase in power for 1341cc, but that's educated guesswork rather than actual testing. Are you still going to do a back to back test for your uni project?