Chris
Bad cop
Old bill are wising onto decats now, they'll have no problems looking under the car and identifying a lack of cat.
On these particular cars though the car can pass emissions with just the precat so I would consider that roadworthy and legal.
Yeh my mate at work had the old bill look under his decatted RX8, but cos of the weird engine he managed to blag them lol. His exhaust is 95db.