Limp mode would suggest overboosting. You've probably tried it all already but if not I'd say you need to check the fitting and the set up of it. You know it has to fit the other way round to the DV I take it ? (ie the pipe normally off the bottom of the 007 comes from the side of the splitter.)
 
I'm not a big fan of the noise from a blow off valve for normal road use so I'd stick with the 007 anyhow. When I was reading up on it I was wondering how it decides how much boost to blow off and how that can be tailored. Still, when you want to make these changes its a bitch when it don't do what it says on the tin.
 
007p with an open cone filter fitted is the best for noise imo. splitter's too hit and miss on these cars.
 
the same 1 i had and the seals spilt in a week
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I just like to save money buying cheap isnt always bad plus, Ive owned a forge 007p its a great product but if I can get this one for £30 then I wouldnt have to think twice its less than half the price and you can use the forge service kit with it including the seal ..