Did the dyno guy show you the 02 readings through out the run ?
If so, can you attach a copy ?
I use the oval and when compared to the 14" round filter on the Mustang Chassis Dyno, there was no difference in cfm, low or high rpm.
Are you positive that your fuel curve was appropriate, you weren't lean ?
We did run a test with the fiber material VS paper. The results were the paper out performed the material once the
oil was applied. Kind of surprising. I will ask my buddy that owns the dyno for more details.