Intake won't
help in a diesel I'm afraid. There's lots of mods you can do on a diesel.....just when it comes to power gains they cost....
In regards to DPF removal I've heard all sorts, for example hollowing it out and welding in some rods...how you would get around the MOT I don't know but I do know that the casing has to be there and ideally not hollow sounding.
Other thing to check I'd turbo boost because if it's overboosting and you get a map the turbo will fail. Performance upgrade options:
- EGR delete - helps with responsiveness and stops recycling dirty air. - need to keep the EGR visually in place to pass an MOT and map out the EGR error.
- Remap - Need to ensure the engine is healthy, serviced, has had cambelt replaced. Is clutch healthy? Healthy turbo? These are all common failure points. Make sure the car is dynoed before a remap.
DPF delete - Needs doing if you go with an EGR delete, EGR delete alone clogs the DPF. I'm not sure if it's changed but people used to modify the DPF casing as to get through the MOT. DPF's really aren't good in that they often clog up and need a forced regen, I'd look into how a delete can be done whilst still getting through an MOT.
In addition to the above, check for error codes using OBD2. Also is it worth first upgrading handling with uprated breaks and suspension?
I've gotten to a point where my cars pretty healthy minus a tempromental turbo which likes to stick. One option I have is a bolt in upgrade turbo but time and money!