200tdi is a great engine.
Get a boost guage and adjust the boost back up to the 1 bar its supposd to have, most of them have dropped to about 0.8 at this stage.
For what its worth and I know most people think they are a con job, I got some worthwhile improvement in bottom end pulling power by fitting a Hiclone, albeit at the expense of top end restriction. I got a measurable improvement (10sec better with as against without 20sec as against 30) in acceleration from 30 to 60 in fifth gear. 0-60 was marginally worse but each in-gear time was better (only marginal in 3rd) with the hiclone than without with, like I said above, a marked improvement in fifth gear indicating a substantive enough increase in bottom end torque - probably as a result of increased swirl before the turbo has come in properly. But like I said I felt that it was restricting the power at the top end as borne out by the worse 0-60 time (1 second worse).
I haven't done enough research into the 200tdi head design to explain this scientifically yet (I don't think the Hiclone could have any benefit whatsoever on a modern engine with well designed swirl chambers) but my measurements showed something was going on.
However the instructions from hiclone called for two units, one just before the plenum and one unbelieveably before the turbo. I think this is part of what leads people to think they are a con job, the turbo would surely destroy any benefit of that one. If I got another 200tdi I would buy a single one. I told the guy I sold my 200tdi RRC to about it as he was buying it as a donor engine for an LSE conversion. He had another RRC and I think he took out the second hiclone and fitted it to his one and was quite happy with it.
Anyway just my pennies worth
BTW I don't sell them or have anything to do with them so this is not a sales pitch, just a bit of advice if you're fitting a 200tdi and think bottom end performance is more important than top.