Hell Horse had similar issues with valve float when using the oem manifolds at less than 10 lbs of boost and switched to only using 4 into 1 headers could be the same thing also I think cutouts help a lot
Change out that clamp on the nipple with a better one that's the style of clamp that leaked on mine. after you do that clean the coolant off and see if the mess comes back.
manifold gaskets wouldn't cause a coolant leak check the hose that connects to the top nipple of the coolant elbow mine had a leak there from a clamp that wasn't strong enough
Where is this 580hp coming from? if a normal Aluminator is a stock hp replacement with forged internals. If you are talking about this motor https://performanceparts.ford.com/part/M-6007-A52XS you can build way better for way less money.
Until results are shown nobody really knows I would bet they are pretty close. However VMP did say on a live stream recently that 1300 hp should be possible on a totally maxed out car and there a plenty of 3.0 Whipples making 1300+ so take that how you will. also it seems that Dustin was talking...
I would do it yourself. as long as you have a good variety of tools it goes together pretty easily. the way I described it was its not hard work but its a lot of work.
I don't see any reason why it wouldn't e85 still produces CO2 and that's what the kit works to detect though e85 produces less c02 so its possible the positive reading might not be as obvious. also that link was for a specific one idk why it would be showing multiples the uview 560000.
If the issue persists use something like this to test the coolant for combustion gases
https://www.amazon.com/UView-560000-Combustion-Leak-Tester/dp/B000NPDL76
I don't like the look of that spark plug
This thread convinced me to get rid of the cats noise can be fixed by resonators or the magnaflow tru x but a plugged cat can destroy an engine
https://www.mustang6g.com/forums/threads/green-cat-failure.134574/#post-2772671
Stick with the 3.0. The 3.8 is a whole lot of blower, palm beach dyno did an interview with Dustin Whipple and they said this blower will not be able to be used with pump gas and is pretty much only recommended for built motor e85
I am assuming you got a tuner kit? Whipple for their stage two kits uses a DW 400 fuel pump. I am pretty sure with a BAP you will still be alright, however, I don't think the 3.625 is a good pulley for pump gas unless you're adding Boostane 3.75 or 3.875 are safer and can get you to your power...