Sorry, I misspoke. It was not a 25% jump in overall performance. I was trying to compare the difference between using just one and then adding a second. The second one was perhaps 1/4 of the performance improvement compared to just using one. It is probably a total of 5-10% in overall performance gains. Which is still significant.
Next, I'm going to try them back-to-back rather than at both ends.
ozzy