I have heard of IRB, looks like they get alot of power from their trucks but can't comment as haven't used them. I did my 200tdi myself and the results are excellent. Takes a fair bit of testing to get it just right. I would NOT do it unless you get a larger inter cooler of some sort and perhaps for greater effect get a mid box delete. A larger one doesn't necessarily mean full size. One like this:
Here's a video of mine after being tuned. It has been faster but for the sake of mechanical sympathy and reliability (so far ) it has been turned back a little. I believe the standard 90 0-60 is 20 secs, mine goes in about 12 ish. Big improvement. Change your fuel filter too if you haven't already.