I run a Magnaflow on mine, ive heard many probs similar with what you are saying with the K1. Im the same as you, i do most stuff myself but dont have access to a ramp so if it needs to go in the air Rutters take care f it for me. I can also recommend
Bedford Auto Panels
01234 217338
Unit 7, Aston Road, Bedford, Bedfordshire, MK42 0JN
They did all my custom body work so may be a better place for welding or moving brackets. Again a very nice family run freindly business.