somebody posted something about jetchip.com on another thread. Here is their response re 400E/E420:

"We do have an ecu upgrade available. The upgrade does require that the factory ecu be sent to us for programing. Average hp gains are 14-17hp at the wheels. The part number is 65002 and sugested retail is $399.00. For further assistance, contact customer support at 800-535-1161. In California, 714-848-5515. Thank You.
Ross @ JET