u should, go into modem(phone) settings and change the settings higher if u want.
I also get 115k connection but speed test is still close to normal 3G speed....so not sure if it'll affect it that much
the 115K may not be the true speed, use a tool such as Netmeter to get a better idea, or run one of the published speeds tests. With the speeds tests, take care to clear your cache on repeat tests.
I did the tests , the gamco one, i get between 145 to 133 ( did 3 tests).
on the settings, both linux and windows its set to the highest possible.
i used vodacom3g's wvdial.conf settings he posted so the config file should be A-ok.