No need to worry for speed capping and all those hassles. You just enter the by default setting provided by Airtel and change HP,proxy and port or Create another setting with new name but previous APN. And everything is ready So Get your settings below. This was tested by me

1) APN:-airtelgprs.com
Proxy:-50.7.78.53
Port:-80
HomePage:-ic.bsbportal.com
Note:This airtel trick support Gmail,Youtube,and ssl site like mediafire and others

2) APN:-airtelgprs.com
Proxy:-4everproxy.net
Port:-80
HomePage:-ic.bsbportal.com

3) APN:-airtelgprs.com
Proxy:-hidethisip.net / 85.17.141.35
Port:-80
HomePage:-ic.bsbportal.com
And Now save above as default and You
are ready to experience the Speed.

Note: don't change nothing
remember but disconnet after 80 MB
i used that 13 GB in 2nd trick