Paul certainly proved that 348bhp from the Cougar could be done using the 2.5 litre engine. It had new pistons and conrods (memory is hazy here but I think the set of pistons cost £900 and the set of conrods the same), a higher capacity oil pump, and the whole engine was blueprinted. I don't know what injectors were used. The supercharger was a belt driven centrifugal type branded as "Procharger". It used a large intercooler as well. The gearbox was an MTX-75 which had been rebuilt and fitted with a Quaiffe limited slip differential. I can't remember what brakes he used, but I seem to remember him saying he wished he'd just spent a bit more and got Wilwoods instead. The car had the BAT 21mm rear anti roll bar fitted. Engine problems were poor running when cold, very heavy fuel consumption under light load and heavy emissions accordingly (the reason it was wound back to 250bhp for MOT and, I think, because Paul wasn't sure if the engine was really going to last that long cranking out 350bhp).
The bodyshop are, I think, what really hacked him off and ultimately made him throw in the towel, although the engine people (Autocraft SVE) were a bunch of crooks themselves who didn't really know what they were doing but knew how to charge money and at least one point held the car to ransom over a dispute over what Paul (and us) considered he'd already paid for and them feeling like being paid twice for it.
Although it can be done, I personally am a bit conservative when it comes to cars, although I do believe I know enough to speak with some level of knowledge. I don't think the Duratec V6 is a particularly good starting point for a highly tuned forced induction power plant, or at least, not for an individual with very finite resources. There are lots of attributes to engines which make them better at doing different things in different ways. All the vacuum and crankcase pressure relieve/breather apparatus for example, as well as the compression ratio do not lend themselves to being happily married to forced induction. Now I know Noble made the Duratec V6 into a successful turbocharged production engine, but it's not quite as simple as just strapping a pair of turbos on to it. Yes, it can be done, but quite a lot of thought needs to go into how the whole package is going to work. The suck-squeeze-bang-blow bit is the easy part. Just where will you get the vacuum for the brake servo from? Most turbodiesels have vacuum pumps to do this. How are you going to lower the compression ratio from 10.8:1 (efficient for natural aspiration) to nearer 9:1 for forced induction. Lower compression ratios are always undesirable but you've got no choice with forced induction - it'll knock otherwise. You can make up thick copper gaskets to raise the heads up off the cylinder blocks, but these have nasty galvanic corrosion issues when clamped between aluminium engine castings. "No problems" is what the garage taking your money will say - they'll rely on never seeing you again. Give it a year and remove the heads for a look though and you'll find corrosion pitting that any decent engine builder will recommend the heads and/or block are scrapped because of. Assuming you do that, you've then got a compression ratio that's suitable but the squish volume (actual volume of combustion chamber with piston at TDC) which isn't great any more, so you need new, different pistons. Alternative parts aren't exactly easy to come by for the Duratec V6. Not a problem for Noble - they can just machine a few hundred at a time for their own use. Not so good for an individual wanting to build ein engine.
In all honesty - and I don't say this lightly - if you want a turbocharged Cougar then I think the 2.0litre Zetec is a better place to start. It has all the same problems as the V6 but the difference is that there are many more people who have already done it and established dozens of ways of how not to do it. There are many more parts available for it, and it's generally just a cheaper, easier engine to work on. There are only half as many cylinder heads for a start!
If you really want to break new ground then that's one thing. It's not for me though. I'll happily do that professionally with other peoples' money but if you just want to make the car go faster in a fashion which you know is going to work, get a Zetec and blow that instead. I'll even flog you a cheap Rover 620ti to strip for the manifolds you'll need, and could use the Garrett T25 turbo as a cheaper starting point to get the rest of it working before you invest big money in a T3 or similar
