[nsp] Tri-homed with HSRP

[tgrace]

We are tri-homed using two 7206VXR's. RTR1 is our HSRP master and hosts a
link to ISP1. RTR2 is our HSRP backup and hosts links to ISP2 and ISP3. We
are getting some performance issues because traffic entering via ISP2 or
ISP3 is returning via ISP1 due to BGP metrics being equal and RTR1 being the
default gateway. Is there anyone way to force traffic out its origin link
when BGP metrics are equal?

TIA for any advice.