I have a PD170, running Revo software, full turbo back exhaust and cold feed air filter.
My turbo back exhaust is a Miltek resonated, inc DPF removal pipe (yours just has a diesel cat not the DPF) and doesn't have any tractor qualities - it sounds like a normal petrol turbo with a resonated system TBH
Currently running circa 220bhp 330lbs/ft (with more power to come ;) ) and don't have a problem with smoke, you get a puff of it if you've been chugging around town all morning then go out on the open road and boot it, but it clears then you get minimal smoke there on !
Both the exhaust and filter made small but noticable changes, maybe not it out and out power but drivablitly
The rev range has increased by aprox 500 - 600 rpm and the car feels alot less breathless
HIH
Tom