mate do you think you can do a test on a DPF race pipe (from chipit) to see if it is worth getting an if they do work
Cant see why not, what results are you after in particular? Power/Torque/AFR/EGT?
If you were closer I'd happily donate my 2008 D40 for some more testing.
Anyway, with custom dump and delete pipe, 3" exhaust and ChipIt chip loaded with a wild tune my D40 is developing around 110kW and 530nm in torque at the rear wheels (265/70/16s fitted) which is around 140kw at the flywheel I think. Anyway, that gets me to get to the current spec 2.5.
I can certainly put more fuel in but I have ran out of air so now need to upgrade the intercooler then squirt some more fuel in.