You sir are brave indeed!
The only issue is that those two big bubbles that used to be cats are going to effect exhaust velocity by creating turbulance because of their shape since they have no internals. The system will defenitely have less restriction than the cats would have had but will not flow as well as the Cat-less Akrapovic X-pipe.
Kudos again for the balls to do this but with the mods you have done to your car I would have expected you to buy the Cat-less Akrapovic X-pipe..... money don't seem to be an issue for you!
2011 E90 M3 ZCP - Individual Moonstone/Individual Amarone Extended/Individual Piano Black With Inlay:LINK!!!
1994 Euro E36 M3 Sedan - Daytona Violet/Mulberry:LINK!!!