You will need to play around with the clamp & spring to get ride of dash light. MIVV supply 2 different length springs to get over it. You solution will work nso stay with it.
The main suppliers for MIVV's in the UK are: MIVV Silencers & Exhausts Speedycom Performance Ltd It might be worth a call, Brian @ BRS is quite helpful although I would play around 1st with what you have there.
You may need to try a different spring, as I mentioned in another post the MIVV comes wit 2 different springs. The other option would be to fit one of these to the servo motor DUCATi 1098 848 1198 BYPASS EXUP VALVE FOR OPEN EXHAUST | eBay
Try give Brian at BR Tuning a call, and purchase the C clamp from Mivv! Alternatively, and I am not sure where you're based, but Chris at CJS will apparently disable the valve via your ECU! Only thing is he's based near Brstol / Bath! Full dyno service £500, but exvl deactivation £ 100 I've heard. Pity your 24p clamp doesn't seem to work....try cutting it with a dremel....the C clamp did work for me, but only if it's right at the end of the cable! Arrow and LV have a similar solution to the one on eBay, which is better, but you need to get to the servo, which is about as fiddly as trying to change the pistons through the exhaust!