I guess there is a problem with the gear ratio. On 5th gear what is the rpm at 60 mph on the new PLUS 4?
On my 2005 PLUS 4, 2200 rpm at ~55 mph. If the car could reach 6600 rpm (max), the speed would be 165 mph (270 km/h) !!!
5th gear is an overdrive.
For me, a real concern, and I guess the maximun speed you can get is with the 4th gear. I never try.
On my opinion, no more power is needed but an adjustement on the gearbox and axle ratio to get 5500rpm or 6000 rpm at 110 mph (180 km/h) and you get the maximun torque at 4500 rpm with a speed of 85 mph (140 km/h) on highways.
The drive will be more funny with stunning acceleration.
