Theres no chance that the vxr can acheive that power with stock boost, His remap must be running stupidly lean or something, they only have 189bhp standard, intercooler wont add hp, it will just keep the boost air cooler resulting in the engine having the power for longer as it will take longer to get hot enough for the engine to dump fuel in at the top end therefore reducing power.
Exhaust will help with the power around 10-15bhp max depending on how restrictive the stock one is.
The remap is accounting for a 35bhp increase minimum.
Would be an animal if it had 300bhp but for the cost of a big turbo kit and stronger pistons etc, he could buy an astra zxr and run that to 300bhp for a lot cheaper.