That sync speed for a 52dB attenuation is reasonable, but could possibly be improved. It would be worth checking your internal wiring - see
here.
In particular try plugging into the test socket - the one revealed when you take the faceplate off. With luck sync speed will be higher. Download speed won't change though as that takes up to 5 days after a better sync. Just report back the stats and see if we can suggest anything.
What sort of router have you got? Some are better than others. I had a Linksys WAG54GS which showed attenuation 52dB like yours, and sync in the mid 6000s, (I have a good line!). Replaced it with a SpeedTouch 585v6 and the attenuation is shown as 49dB and sync around 7000kbps. So I gained a profile jump just like that! Even the SpeedTouch can be bettered judging from what I see round here. Just refurbished from DSL Depot it only cost �24 inc postage.
Is the house just new to you, or is it a new build? If new build, did the builders put in the extension wiring? I believe they often use poor cabling.