I've been told by a friend of mine he had a 25 hp loss using a BHAF . Based on research I find that hard to believe. I'm about to put one on my truck this next week and like to know if I should proceed or not.

Nope. During the time of hose clamp vs. turbo I asked around to a bunch of vendors about upgraded turbo with my exhaust brake. No one had a upgrade for me at the time nor any suggestion of turbo that would fit the Jacobs brake. That's why I still have a stock turbo. Everyone suggested I ditch my exhaust brake then I could upgrade. But to keep it I have to keep the HX35W turbo.

I will have to do a little checking, I was fairly certain I had seen a turbo or two that use the OEM elbow, and thus the EB would work. I do believe the Garrett is one option.

Still not quite willing to believe it yet... (personally). So from -20*F to 110*F net me 24% loss. Well maybe seem a bit steep... Food for thought. Some of my basis of the warmer air idea. Also looking at ISX without a fan and warmer temp he creates. http://www.dieselpowermag.com/tech/general/0708dp_1997_dodge_ram_3500_dualie_cummins/viewall.html

I see it in aviation very easily, as well as in my truck. On a warm truck the load is noticeably higher in winter than summer, for the same weight and speed. EGT's aren't similar based on ambient temp, and even boost is effected, but load is pretty accurate.