My CAI setup
Holes drilled for more airflow
I had a K&N 6.5" long air filter on the APS intake because I didn't get the APS one with mine. Initially my data logs were showing a reduction in airflow, so after a bunch of messing with the tune, I changed back to my under hood filter (GST "OMG" filter, or whatever you people call it)
I wasn't happy with the change in drive ability with the under hood filter, plus the IAT's were also a lot higher. So I found a 9" long dry air filter. I went back to the CAI. This time airflow was up. But top end airflow was still not very good. Drilling the holes helped this out.
My AFRs went very lean, (especially with spool up) so be careful.