Bypass catchall SNAT?

We have a default catchall SNAT for internet destined traffic, however I'm trying to get the F5 to route traffic internally to a private network without SNATing. I created a forwarding virtualserver without SNAT and pointed it the the gw. However, the F5 SNAT's the source ip before forwarding on to the gw. I've tried the following iRule without luck:

when CLIENT_ACCEPTED {

if { [IP::addr [IP::local_addr] equals 10.1.1.0/255.255.0.0] }{

snat none

}

}

Any assistance in making the F5 just route the traffic without SNATing would be helpful.

Thanks.