Is there a way to get better downloading preformances by modifying the number of PDP context ?

I did modify the /system/csc/customer.xml on android with value of <NbMaxPDP>10</NbMaxPDP>
And I could see the difference when browsing.
The download bit rate is the same but there are more channels to donwload. So the buffers are filled faster.
If my souvenirs are correct, in 2G, 11 or 21 PDP context were possible...

If i look on ofono the MAX_PDP_CONTEXTS is define to 2 in the RIL and 4 for st-ericsson part.

Is there another config-file, for operators, that manage the number of PDP context ? (this would avoid to recompile the modem binary)