I am sure somebody will correct me if I am wrong but I am sure the downstream spec is -7 to +10. That being said, a 10db fpa seems a bit excessive and is taking you from one extreme to the other and I would be tempted to go with an 6db fpa and see if that improves things.
https://www.amazon.co.uk/Forward-Pat...t-items&sr=1-1
Where do you live btw?