If it's properly setup a QA42 can really move snow. Here's my #2 125 with a tired K301 moving wet March snow back in 2001. The QA42 has the inside of the auger housing and discharge chute coated with graphite paint to make it nice and slippery.I didnt thing the single stage were that good .
I don't think you'd need it and there may not even be available...that's a 2 stage blower. I'm not familiar with the MTD made Cub attachments and I'd be afraid of damaging your 451.i have a 451 on my newly purchased 2084, should i look for a speed up pulley for it ?