If the DPF is healthy and regenerating without issue then you can leave the DPF ON and tune it within the regen cycle capabilities... if its weak and as long as there are no ECU errors for DPF (this bit is key as the errors are logged in a seperate part of the ECU and notoriously difficult to remove once the DPF fails) then you can remove DPF, install a bypass pipe and successfully map out the DPF, EGT sensors etc and make better power.
If you're installing a bypass pipe, ensure it's a decent quality item with flange connectors. I've seen everything from chop shop rubbish to some numpty even 'smashing' his DPF through (and destroying the EGT sensor in the process, and pushing the crap back into the turbo)!!
If you're going to do something like this, do it right first time.
