I have 2 bird meters. One has a aftermarket PEP. The second is a true bird 43P. The true 43P shows 2 or 3 more watts than the add on kit. I am talking Diawa showing about 20W less power. On my 100W radio. I also compaired it to a LP100A. And it was also unacceptable. I will end up sending it back for recalibration. I love the size of the meter and ease of seeing the SWR at a glance. But I must say a bit disappointing.Compared to what? The Bird? Does the Bird meter have real pep measurement capability?