JTeague,
I missed your post until now

Well, if it follows that the lower the plate # the more the fuel, then the #4 will flow more than the #5. However, the #4 isn't rated, so probably close enough.
Here's what I found out about the #8. I ordered my 1st plate, the #12. Put in the plate, centered, WOW, smoke, the rear end squatted down, light front end & be careful passing, those rear bumpers come up real fast.

EGT measured post turbo was 950 degrees @ 32psi, probably safe.
Then I ordered up the #11. Took off the AFC housing & uh-oh, there was a #8 in there.

I never checked the #, I thought it was a #12. Oh well, so in went the #11, centered.

Big disappointment. Drove home & slid the #11 all the way forward. Now it was equivalent or maybe a tad better than the #8 centered. EGT the same. That was probably in the 340hp territory.
Sometime later, I moved the probe pre-turbo & hit that 1500 mark in a hurry.

Time for a less restrictive Monica.
The HX40-16 lowered EGT tons.

Off idle spool up was slow but it made room more fuel. So, in goes the #8 slid 3/4 forward, 1300 max. What, room for more fuel? Here comes the #4.
Bottom line, in my experience, in order to use the #8 or below, you've got to change turbos to relieve restriction, lower the compressed air temp & make the engine work easier. Advancing timing helped, but didn't measure. The BHAF definately reduced EGT & also all but eliminated the off idle spool up.