Sooo...

you've broken the cat up in the pipe then?

Possibly blocked the pipe and increasing back pressure causing it to cut out?

Have you had the pipes off and given them a shake, see if they rattle?

Just food for thought.

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09 XT660X:

CCC Stainless Rounds, Stage 1 DNA, Stage 2 DNA, PCV With Custom Autotune Map, PCV AutoTune, Home made O2 eliminator, Self machined Fork Spacers, DIY Autotune Switch.