I have the prc 2.5 5.3L heads. Not sure if you were following the thread but I ran a 12.10 with it sunday. My tune is hit or miss though really was probably leaving some on the table. The biggest plus to my set up is it's a great street mannered car. I could drive it everyday if I had to.
I have no idea.....it's never been dyno'd.
I'm always driving it. I've seen quite a few - red, black, SOM, silver...
It will make a slight difference in stall speed at least brake stall. Flash stall wiill remain the same
No its used for the build on the converter ,