Default Intake air temp

I went to the track this past weekend.It was in 80's with high humidity.The intake air temps were reaching 185*.
My question is,,,,at what IAT will the power be effected and start falling off??
AFR was 13 @ wot.I have a 1071 BDS roots and after a few passes I increased the boost from 6 to 8 to 10 and the MPH only increased 3 MPH
I have been 9.3 @ 146 with 6 lbs through the 4 inch exhaust and it was choking with reversion.This weekend I uncapped the dumpers and hoped the crack the 8's but couldn't get faster than 9.6 with 10 lbs of boost. That was 28* timing and 13 @ wot.
Engine is a 545 2nd gen hemi with fueler aluminum heads.

I was rather disappointed!