Bosch performance line CX Motor mod help please

Hi guys,

Recently purchased the KTM Macina force 293 electric bike with the Bosch performance line CX motor.
I love the bike however when I hit the 25kph mark it's like trying to ride through mud! So I'm thinking about modding the motor. I would prefer to do the internal mod so no extra parts needed etc. Please could someone give me an idea of price and where I can get it done preferably in the Nottingham area.

Thanks

Whatever you do immediately voids the warranty, and some shops won't even work on it at all afterwards if the computer shows Bosch its been modded. With the really simple speed box type external mod (the kind the just fools the speed sensor, and shows half of the true speed and distance on the display), at least it doesn't show up on the system when its on the Bosch dongle.