This is my first posting, so please excuse the length, but I read this thread and thought, this just happened to me.
I've just had my 2008 2.4 JTDM Brera remapped, DPF and EGR disabled by Gareth of Avon Tuning, just north of Bristol and*He had a real problem with the car.
The DPF removal went to plan, disabled correctly (took a while to remove all references to the DPF) and the EGR blanked and disabled correctly.
A stage 1 remap was done (best economy) but upon road testing, the car's boost went off between 2000 and 3000 rpm. He thought there was problems with the EGR and tried numerous things, but it still had a problem. *No problems with error codes etc, the car was otherwise fine.
3 hours extra later, he found the problem. My car (2008 model) has a torque limiter in the ECU, to protect too much torque damaging the clutch. He'd dialed in and extra 80nm of torque and that was just too much. So, he reduced the torque to 75nm and raised the bhp slightly to compensate and the boost is now solid all the way through, goes like a train.
So, I would see if you can get the torque curves checked on the remap, this was definitely the problem with mine.
Oh, and I have to say that Gareth was very knowledgable and thorough in the remap (I'd done a lot of forum reading up before speaking to him and he knew everything To look out for and more).