Don't make the mistake I made, modify it before you get it remapped.
What I'd recommend for an AGU is -
K03s Turbo - Bolt on fit and can pick up cheap.
Front mounted intercooler (or wellycooler)- you might need the r32 front bumper too, to house it.
Performance exhaust - Milltek are one of the popular choices but maybe a bit expensive for you.
S2000 Filter or a Pipercross panel filter, your choice.
Forge 007p / 008 Recirc valve.
A larger turbo intake pipe (TIP).
Then get it Remapped.
Shortly after the remap you might see your clutch slipping, in which case, upgrade it to -
VR6 / G60 Clutch / Flywheel
With all of those mod's you would see an easy 230bhp.
Without changing the turbo you'll see about 180-200bhp.
I'm sure there's stuff I've missed, but that's the main stuff.
(copied from a similar thread)