> Have a problem with 403 errors

Probably a protection against offline browsers like 
httrack - the problem does not appears on all websites, 
isn't it?
You can bypass these kind of protection, BUT only with 
GREAT care:
- setup bandwidth limits (example: 5000 B/s)
- a maximum of 2 simultaneous connections
- check regularly if the mirror is not looping forever

After setting these limits, you can change the browser 
identity (set options/browser id). But, again: limit the 
risks of bandwidth abuse!