RAF. Unless it has an obvious problem, then spend at least six months shooting the FTP900 in standard form.
Regardless of previous shooting experience, changing things at this stage is a variable you can live without.
Once you have got to know the rifle and your shooting has settled then if you still want to bling it up and mod it, at least you will be able to see what effect the changes to the rifle make, both good and bad.
"I'm your huckleberry, that's just my game"