Trafic 2011 hybrid turbo

Hi. I own a 2011 Trafic. It's been remapped and its pretty quick for a van, especially on the motorways. I've had a quote for a hybrid turbo, just over £500 which I think is very reasonable. However, as I'm pretty new to Renault ownership I'm constantly hearing horror stories about the gearboxes packing in. I've asked around several transmission places to see if there's anything that can be done to strengthen the pk6 but my search has turned up little info. I've been told the box is at its limit at ~150hp. I'd love to get some more out of it, I'm under no illusion that this is going to be cheap but refuse to rule it out until I've had a 'no it's impossible' or 'bloody hell, how much?' Are there different variants of the pk6? For example, does the 2.5 Trafic have an identical box, would it even fit? It seems such a shame to have an engine with potential and have the gears as the bottleneck. What about a box from a different m9r, e.g Megane? I'd guess putting a car box on a van is a no-no. If I was younger and a little reckless I'd probably just go ahead and cross my fingers but as reliability is quite important I will have to exercise some restraint! Thanks

Trafic 2011 hybrid turbo