That should be fine. 400 would be hideous unless your towing a horse float or 6m boat full time.
Consider a set of Polyair air bags that fit inside the coils if your concerned. Spring tower brace for the win too.
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Finally got the OME +200kg kit installed today.
Pic below:
Attachment 74775
So far so good, seems to handle ok and the ride feels fine.
Had a chat about airbags for the rear. Will wait and see how the rake/height at the back settles after a couple of towing trips.
Cheers,
Shane