The system comes in 3 parts if you go for the Downpipe, centre and backbox option. You could fit the centre and backbox just now (four bolts) and buy and fit the Downpipe when you are ready to remap. Power gains with a full decat system, uprated fuel pump and an Andy F remap can be considerable for starters.
Beyond that the world is your oyster
Cheers
Gus