If you want a warranty, dont put them back in - you'll pay £500+ to swap them out and back each time you want to claim.
If you want the power, dont renew the warranty and save the money for bills. I dont have a warranty and just replaced the turbos, but at least I can use good indies rather than the muppets at the dealer. Pay to play!
Car: 2010 Jaguar XFR (Stock - For now)
Gone but not forgotten: Highly Modified E90 335i LCI M Sport Manual (circa 480BHP/500lb ft)