When you are pleased with the FTP900 as it is ... Leave it alone
Standard the FTP is an amazing accurate piece of kit, well made and I consider it the best rifle in my collection. Where I have the need with other rifles to fiddle with them and improve things, the FTP is very good as standard.
The only thing I did was make it lighter, with the carbon shroud and other muzzlebreak, and therefore it is now free floating. For cosmetic purposes mainly, it did not shoot more accurately
... But almost a pound lighter matters to me and standing and kneeling shots have improved. Or it is the practice