280bhp is a high number for a stock engine however, people pull those figures all the time on TD04? The only question is really, how long will the stock internals last... It's easy to get 280bhp with a TD04 though.
It pretty much is down to a good map. Providing all the other stuff holds up mechanically, the only thing that produces the power is the map.
A ct9 hybrid is still a ct9, so it uses the same manifold, downpipe, lines etc etc.
I suppose that technically they didn't map it as they didn't change any of the map itself, however if they did spend a few hours turning the boost up, and then playing with the fuel cut defender and your regulator then I guess that's the best they can do without a ECU that can be mapped... If you went in with 134bhp, they set it up and you paid £200 then came out with 195bhp with a graph, I wouldn't complain haha .