The Scotstoun side travel to Dublin for Saturday's semi-final as they face a Leinster side that has won three out of the last four Heineken Cups. But Townsend hopes his side can take strength from their 20-3 triumph over Connacht in Galway last week and use it to cut down Josef Schmidt's Blue giants.
"Leinster have set the benchmark in European rugby for the last four seasons and we are under no illusions as to the size of the challenge that awaits us in Dublin," he said.
"Winning in Galway has created vital momentum for us after our home victory against the Ospreys. It was also important that we were able to deliver a quality performance away from home against tough opponents. We return to Ireland this weekend with renewed confidence and determination.
"We narrowly lost to Leinster in March but we were pleased with a number of aspects of our game that night. We've improved since then and we're really looking forward to another opportunity to play at the RDS."
Townsend has made seven changes and one positional switch to the side that won in Galway, with Peter Horne moving from inside centre to fly-half and Ruaridh Jackson dropping to the bench.
Alex Dunbar comes in for Horne, with Stuart Hogg, Sean Maitland, Niko Matawalu, Josh Strauss, Al Kellock and Ryan Grant also back in the starting line-up.
Hogg replaces Peter Murchie at full-back, Maitland comes in for Tommy Seymour on the right wing.